Frying 7900GT boards

When my first 7900GT board started to behaving strangly, I thought it had to do with all the experiments and changes I had made to the board.

I bought a second 7900GT board, and modified it to 1.5 Volt GPU and 2.14 Volt Mem and added a Zalman VF 700.
GPU temp was never higher than 62 C, and everything worked fine for two whole weeks until yesterday. As a first sign, the board started dispaying huge artefacts in "Deep Freeze", the last test of 3Dmark06. After that happened, I had to restart the system to get the display working again. 3Dmark05 still worked troublefree at that time.
At the end of the day, ever more problems ocurred, and now I cannot even run 3Dmark05 anymore.

It seems to me that the G70 GPU is not able to have 1.5 Volt on its pins permanently as well in the 2D as in the 3D mode.
With 1.5Volt it seems to be an accident waiting to happen.

With my experience based on two boards, I can only advice: Do not apply more than 1.4Volt on the GPU, or even better have a board that only has a higher GPU voltage when in 3D mode, like the EVGA SS serie.

The 7900 GPU is nowhere as robust as the 7800 GPU, since I never had the slightest problem with the last.

I am considering now to buy a 9750, mod nothing at all and return it under RMA if anything goes wrong. All I need is the right BIOS for my P5WD2-E.

Hmmmm... So even with the switching mod and everything, the board still fried?

Quote:

---

Originally Posted by couppi

Hmmmm... So even with the switching mod and everything, the board still fried?

---

Yes with all the mods. The board has been modded with the greatest care with SMD resistors only: 50Kohm for the 1.5Volt , 100Kohm for the switching mod and 10Kohm for the 2.14Volt Vmem mod.
From a distance it is hardly possible to see that the board has been modded. All possible negative side effects of having long wires and/or having mechanical instabilities have been completely avoided by using these SMD resistors, but nevertheless .....

So you think it's the core, not mem which has failed you?

did you sink all the hot ICs on the back of those boards ? those could be the cause for artifacts as I have read from EVGA forums.

I've had trouble with that freezing thing as well, am able to run 3dmark05 no problem... Haven't tried 06 yet, but sounds like i should.. As far as I have been told, it's the MOSFETs and voltage-regulator on the back of the board which overheats... Try de-clocking your RAM :)
I'm running mod-free btw :)

Best Regards :toast:

All I've done is ground the two points at the top of the board that yield +.1v and +.2v respectively. I've had my card since the day they came out and have had the mod running just about as long and no problems here. I have the eVGA CO 500/1500 card.

Quote:

---

Originally Posted by ManagHead

So you think it's the core, not mem which has failed you?

---

The board still works in 2D with the high memory clock, only when 3D starts I am getting problems.
Going from 1.2 to 1.5 Volt is a 25% increase for Vgpu.
Going from 2.04 to 2.14 for Vmem is only 5% increase.
The memory is similar to the memory on the 7800Gt board.
According to Samsung, the max voltage on the memory is 2.5Volt.
So if I take all this into account, I bet it is the GPU that is making trouble.

Quote:

---

Originally Posted by Krizby87

did you sink all the hot ICs on the back of those boards ? those could be the cause for artifacts as I have read from EVGA forums.

---

I have made proper cooling with heatsinks to the Mosfet and the voltage regulator. Temp stays below 40C

Quote:

---

Originally Posted by DTU_XaVier

I've had trouble with that freezing thing as well, am able to run 3dmark05 no problem... Haven't tried 06 yet, but sounds like i should.. As far as I have been told, it's the MOSFETs and voltage-regulator on the back of the board which overheats... Try de-clocking your RAM

---

Thanks for your suggestions. It is not "freezing" that is happening. The board starts wildly artefacting when in 3D, and when I interupt and go back in the 2D mode, the 7900GT is displaying partly rubbish on the screen and is no longer controleable. Only by restarting the system, everything is working properly again in 2D.
Declocking the GPU and/or MEM does not help me in any way !

are you using coolbits or atitool for clock adjustment? or something else?
i found some cards really don't like coolbits
maybe try nibitor bios program and see if you can change the delta clocks and/or some other settings.
just a couple of ideas.
good luck

I lost 2x Asus EN7900GT in three weeks (first GPU@1.4V with VF900cu died in a week and second one died in two weeks it was watercooled GPU@1.55V ,ddr@2.2V it did nice 735/1030 artefact free:mad: ).
I had no problems with Club3d 7900gt which i ran @ 1.55V,2.2V for two months and is still running fine with the new owner.

Quote:

---

Originally Posted by t024484

Thanks for your suggestions. It is not "freezing" that is happening. The board starts wildly artefacting when in 3D, and when I interupt and go back in the 2D mode, the 7900GT is displaying partly rubbish on the screen and is no longer controleable. Only by restarting the system, everything is working properly again in 2D.
Declocking the GPU and/or MEM does not help me in any way !

---

What you describe there is the same problem I have when oc'ing... At stock it runs fine, but it takes almost no oc before it starts acting like that... it runs benches (3dmark and AM3) with pretty high clocks, but no games are possible... It was possible the first 2-3 days, then it started... Dunno if that's the same thing you've expirienced??

Best Regards :toast:

This problem is well know on some brands of 7900's esp evga and xfx which have problems, some remove deltas in bios as thay can be as high as +40 which gets higher as you overclock and if your card only overclocks for a period of time then wont run anything but stock, you need reflash bios and it will again overclock, someone pointed towards not using coolbits to overclock till this is fixed.

There is many threads about 7900's issues esp them 2 brands but not just them.

Quote:

---

Originally Posted by flytek

are you using coolbits or atitool for clock adjustment? or something else?
i found some cards really don't like coolbits
maybe try nibitor bios program and see if you can change the delta clocks and/or some other settings.
just a couple of ideas.
good luck

---

I am using Coolbits, and also Ati Tool and Riva Tuner.
I have noticed no difference between the three when I change the Clock.
The point is however that everything worked fine for two weeks, and now the damned thing starts to desintegrate.
I have tried delta clocks with Nibitor of 0, 20 and 40 but with no effect.
Something starts to misbehave as soon as 3D starts, no matter what the clocksetting is.

Quote:

---

Originally Posted by Shark-357

I lost 2x Asus EN7900GT in three weeks (first GPU@1.4V with VF900cu died in a week and second one died in two weeks it was watercooled GPU@1.55V ,ddr@2.2V it did nice 735/1030 artefact free ).
I had no problems with Club3d 7900gt which i ran @ 1.55V,2.2V for two months and is still running fine with the new owner

---

This is just another prove that the 7900GT is still very vulnerable for whatever, and that Nvidia should spend some time in getting things better under control.

Quote:

---

Originally Posted by humeyboy

This problem is well know on some brands of 7900's esp evga and xfx which have problems, some remove deltas in bios as thay can be as high as +40 which gets higher as you overclock and if your card only overclocks for a period of time then wont run anything but stock, you need reflash bios and it will again overclock, someone pointed towards not using coolbits to overclock till this is fixed.

---

As far as I am corrrectly informed, all boards come from the same manufacturer in China, so if this is true, there are no differences, apart from having more components on the board like the EVGA SS.
Reflashing the Bios did not bring anything, nor did changing the delta.
I have also reinstalled the Forceware driver and Direct X9C, but all with no effect.
I will see what happens if I do not install Coolbits.

The issue with these cards is the memory NOT the core...
The mem mod you did would probably have accelerated any damage being done to the memory regulation, bet you didnt add any extra cooling to the rear of the card either?
Some of the cards seem "worse" affected than others, if they make it passed the first 2-3 days of their lives without artifacting/having issues with Deep Freeze in 06 then chances are it'll be fine.
Just had an XFX card die on me, ran fine for the first few days then the deep freeze issue presented itself. From then on things got worse and worse.
Not getting XFX again, probably plump for another EVGA CO as this ones been pretty decent so far...

Quote:

---

Originally Posted by Highland3r

The issue with these cards is the memory NOT the core...

---

I tend to agree with you. But I think it's a combination memory / volt controll components.

Maby it's a crapy batch that does not hold a steady voltage regulation as the tempratures rise. After the inital break (pushing the components to the first breakdown), the behavior presist or are easier to provoke.

My eVga also started making some high pitched sounds, like a MOSFET or IC on the last leg. Pointing to problems with freqs switching.

I just don't know what's up with some of these cards.

I've had my XFX at the speeds in my sig since day one of ownership, no mods, no problems to report either.

Quote:

---

Originally Posted by BigDov

I've had my XFX at the speeds in my sig since day one of ownership, no mods, no problems to report either.

---

I get the problem every time I loop DeepFreeze in 3Dmark06.
First run went fine, every run after initial gets massive tearing.

Tried all different drivers...and so on.

Quote:

---

Originally Posted by Highland3r

The issue with these cards is the memory NOT the core...
The mem mod you did would probably have accelerated any damage being done to the memory regulation, bet you didnt add any extra cooling to the rear of the card either?
Some of the cards seem "worse" affected than others, if they make it passed the first 2-3 days of their lives without artifacting/having issues with Deep Freeze in 06 then chances are it'll be fine.
Just had an XFX card die on me, ran fine for the first few days then the deep freeze issue presented itself. From then on things got worse and worse.
Not getting XFX again, probably plump for another EVGA CO as this ones been pretty decent so far...

---

I already mentioned that I have cooled the Mosfet and the Voltage regulator, and that they do not get hotter than ca 40 C.
Why are you so sure that the Memory is causing the trouble, it will be interesting to hear if you have more info to share.
My Vmem seems as stable as a rock as far as I have seen so far, but I will investigate this further with my osciloscope to see if anything is behaving strangely around the voltage regulator.

Quote:

---

Originally Posted by t024484

I already mentioned that I have cooled the Mosfet and the Voltage regulator, and that they do not get hotter than ca 40 C.
Why are you so sure that the Memory is causing the trouble, it will be interesting to hear if you have more info to share.
My Vmem seems as stable as a rock as far as I have seen so far, but I will investigate this further with my osciloscope to see if anything is behaving strangely around the voltage regulator.

---

It seems (from reading around and personal experience) that if the cards going to die it will. I'd suggest its not the mods which are killing the cards, (although they may well accelerate death) just the fact that the cards going to die anyway.

The reason I say its the memory which is the issue is thus: Overclock a 7900's memory too high games/benchies "appear" to run clean, but on going back to desktop it seems to flash/corrupt. Downclocking the memory fixes the issue.
Just lost an XFX card, the regs were sinked and a 120mm fan blowing over them. 3 days after getting the card (and running SLI) arti's/hangs started to occur. The usual symptoms of a dying card.
On running 03 and other 3d a day or 2 later the card produces the same flashing screen etc as the EVGA did when the memory was clocked too high.
To me that suggests the memory is the cause of the issue in this (and probably other) cases.

Quote:

---

Originally Posted by Highland3r

It seems (from reading around and personal experience) that if the cards going to die it will. I'd suggest its not the mods which are killing the cards, (although they may well accelerate death) just the fact that the cards going to die anyway.

The reason I say its the memory which is the issue is thus: Overclock a 7900's memory too high games/benchies "appear" to run clean, but on going back to desktop it seems to flash/corrupt. Downclocking the memory fixes the issue.
Just lost an XFX card, the regs were sinked and a 120mm fan blowing over them. 3 days after getting the card (and running SLI) arti's/hangs started to occur. The usual symptoms of a dying card.
On running 03 and other 3d a day or 2 later the card produces the same flashing screen etc as the EVGA did when the memory was clocked too high.
To me that suggests the memory is the cause of the issue in this (and probably other) cases.

---

Thanks for your reply. I will try to dig further into the problems, because there are things that are illogical to me.

1) I run my memory at 1750 Mhz as well in 2D as in 3D mode. No signs of trouble are there as long as I stay in 2D with this high memory clock.
The memory is unaware wether you are using the system in 2D or 3D, so how could the memory cause trouble only in 3D ?
2) Samsung gddr3 memory is used all over the world, in all kind of graphic boards, and I have not heard of similair problems in other high end boards.
Also the 7900GTX with the same memory chip in a selected 1.2 spec does not seem to cause any problems with frequencies up to 1800Mhz.

My suspicion is much more that it has to do with electro erosion within the GPU.
With the smaller 90 nm details, it is more critical then ever to keep signals carrying different voltages apart far enough, more critical then it was with the 7800 GPU with 110 nm details.
When you have 1 volt difference on traces only 100nm apart, this translates into 10.000Volt/mm. This is enough to fire a spark plug.
Things are made even worse when you increase the Vgpu.

If signal traces are too close, you will see an avalanche (or electro erosion) taking place after some time, which in effect causes the same destruction as a short circuit. Just by small individual differences in the production process, on one chip the distance can be several nm more then on another chip, which leads to one chip dying quite soon and the other staying alive for some time.

So it is much better if you only allow the higher Voltage when in 3D mode like the 7900GTX and the 7900GT SS are doing, that's probably the reason why, because most of the time a PC is working in 2D.

If my suspicion is true, it will force NVIDIA to come with a redesign quite soon.

In 3D there must also be other parts of the core that get activated. Parts that lay dormant in 2D.

Strange it's tearing in whole lines as I've heard is a indication of memory problems.

What about different power IC beeing used in 2D and 3D?

Just tossing some ideas out there.

I've been reading that alot of ppl get issues in DeepFreeze (3Dmar06), including myself. Downclocking the core does nothing.
Taking the mem to nVida stock speeds is another ting, DeepFreeze passes without insident; if one does not take into consideration the crapy score ;)

Quote:

---

Originally Posted by Lerun

In 3D there must also be other parts of the core that get activated. Parts that lay dormant in 2D.

Strange it's tearing in whole lines as I've heard is a indication of memory problems.

What about different power IC beeing used in 2D and 3D?

Just tossing some ideas out there.

I've been reading that alot of ppl get issues in DeepFreeze (3Dmar06), including myself. Downclocking the core does nothing.
Taking the mem to nVida stock speeds is another ting, DeepFreeze passes without insident; if one does not take into consideration the crapy score ;)

---

It is not tearing whole lines, firstly things are happening randomly and then the screen starts flashing, which only stops after a complete restart. The same power IC´s used for 2D are also used for 3D

You can also fix it by reloading the gfx drivers via rivatuner :)

My 7900GT is dying. I have used 1.5V all the time from day one, but randomly screen flashes, goes black or tearing. Only help is that Max Vgpu is 1.5V or under and no mem mod. I think my problems are mem related.

Core can still do 700 but mem do only 1600. Anything over 1600 and screen starts to act weird or flash after 3D mode.

Every temperature are ok.

if you have a samsung ram on the card, I suggest flashing it with EVGA beta bios as this Bios is supposed to fix issues with the memory -> flashing particles, screen goes black. See if it help.

http://www.yousendit.com/transfer.ph...5C91575BA7C88E

I also have the screen flashing thing when I overclock memory too high, GPU core would downclock to bios clock, FEAR benchmark would run fine (with lower GPU clock) until I quit the game and the screen went nuts, seems like the refresh rate goes down to 2 or something, if I move the mouse the screen will flash, every movement on the screen will make it flash.

Quote:

---

Originally Posted by Krizby87

if you have a samsung ram on the card, I suggest flashing it with EVGA beta bios as this Bios is supposed to fix issues with the memory -> flashing particles, screen goes black. See if it help.

http://www.yousendit.com/transfer.ph...5C91575BA7C88E

I also have the screen flashing thing when I overclock memory too high, GPU core would downclock to bios clock, FEAR benchmark would run fine (with lower GPU clock) until I quit the game and the screen went nuts, seems like the refresh rate goes down to 2 or something, if I move the mouse the screen will flash, every movement on the screen will make it flash.

---

Cool, just can't seem to dl the file. Is there an alternate place to get the file?
Do you know if they changed the mem timings to make them more stable?

I'm trying to be fair to companies and not RMA cards I've modded. That's why I want a 100% stable card before I start in with the soldering iron. Even if they can't detect the mod once I remove it.

Quote:

---

Originally Posted by Lerun

Cool, just can't seem to dl the file. Is there an alternate place to get the file?
Do you know if they changed the mem timings to make them more stable?

I'm trying to be fair to companies and not RMA cards I've modded. That's why I want a 100% stable card before I start in with the soldering iron. Even if they can't detect the mod once I remove it.

---

Ram timing is the same 31/39/22/9/10/6/8.

I will try it and see what happens.

Quote:

---

Originally Posted by SF3D

My 7900GT is dying. I have used 1.5V all the time from day one, but randomly screen flashes, goes black or tearing. Only help is that Max Vgpu is 1.5V or under and no mem mod. I think my problems are mem related.

Core can still do 700 but mem do only 1600. Anything over 1600 and screen starts to act weird or flash after 3D mode.

Every temperature are ok.

---

"Only" 1600 for an unmodded Vmem is very, very good so I do not see anything abnormal there. When you get outside the maximum limit, everything can happen.
I simply do not understand why so many of you are pointing in the direction of the memory.
There are so much more arguments why it concerns the GPU, and I cannot find one single logical reason why it should be the memory.
A memory chip that malfuntions in 3D should also malfunctions in 2D, which is not the case here.
The 7900GTX has no problems with the same chips, etc, etc.

Quote:

---

Originally Posted by flytek

are you using coolbits or atitool for clock adjustment? or something else?
i found some cards really don't like coolbits
maybe try nibitor bios program and see if you can change the delta clocks and/or some other settings.
just a couple of ideas.
good luck

---

Flytek and Humeboy suggested not to install Coolbits.
I could hardly believe that this was going to get me any further, but for the sake of trying, I installed forceware again without coolbits and used rivatuner instead , and guess what ???

Everything works again just as troublefree as before the problems started.
I have no explaination why a systems works properly with coolbits, then starts desintegrating and when finally replaced by rivatuner everything works fine again.
I am still very suspicious if this is going to stay, or if it is just a short delay in the dying process.

Quote:

---

Originally Posted by t024484

"Only" 1600 for an unmodded Vmem is very, very good so I do not see anything abnormal there. When you get outside the maximum limit, everything can happen.
I simply do not understand why so many of you are pointing in the direction of the memory.
There are so much more arguments why it concerns the GPU, and I cannot find one single logical reason why it should be the memory.
A memory chip that malfuntions in 3D should also malfunctions in 2D, which is not the case here.
The 7900GTX has no problems with the same chips, etc, etc.

---

The cards when they die exhibit the SAME symptoms as they do when the memories oveclocked too far. The vMem regs get MUCH hotter than the vGPU.
The GTX may use the "same" chips, BUT the regulation on the GTX is MUCH better than that of the GT. IF Nvidia used the same regulation on the GT as they did on the GTX then the GT's would simply be downclocked GTX's. They'd loose money.
The vMem regulation IS the issue on these boards. Not sure why a driver reload/reboot fixes the issue, sure theres someone with 1000* more knowledge on the subject out there.
The memory in 90% of the cases IS the issue with these cards.

<edit> As for the 2d/3d issue, the cards NOT loaded in 2d whereas it is in 3d (no s&*t sherlock...). Belive the issue is overloaded regs which overheat and crap out. Hence not occuring in 2d mode.... </edit>

Hmm.. would be worth a try, have the same problem as you, having Coolbits installed... :)

Best Regards :toast:

Hey Guys,
Although there seems to be lots of threads in other forums this was one of the first ones I've read over here at extreme systems (I thought all you guys knew something none of us did), lol! Like many I have also had these problems, in fact I'm on my forth eVGA 7900GT RMA replacement. With the first 3 I began having the problems within 4 days of installing the card.

Then about 3 weeks ago eVGA announced that there was indeed a hardware based "Issue" that they had fixed by "Slightly Modifying" the replacment cards they were sending out? Of course they have been very vague about it the fix, where it is and what it is? So 1.5 weeks ago I filled out a special form they had on their message board for people who have been persistantly having the same issues with their 7900GT's, they said once the form was submited they would call/e-mail the persons back to take care of it. Well the next day I got a message from a Jacob Freeman who sent me a special "Cross-Shipment Authorization" form so that I could get my "Slightly Modified" replacments card first, and then ship out my third defective card within 30-days.

Then about 3 days ago I got my replacment which was the Signiture Series card with a modified BIOS so that the clockspeeds would match my 7900GT CO card (500/1500Mhz). Fingers crossed so far it was been working great even though I've been doing some serious gaming/benchmarking to push the card. This card does indeed run at 1.45v in 3D mode and 1.2v in 2d mode (checked with multi-meter). I'm not exaclty sure why they would do this except maybe that these cards have had a better track record so far with RMA's?

I realize that the SS card is fairly new in eVGA's line up but does anyone know if they actually do have a better track record than the other cards? When I put both my regular GT CO card and my new SS card side by side to compare the components they are certainly different in many ways. I'm no expert so I'm not sure what componets do what but I do know they are differnt in many ways. Well thanks for any help you can give guys and good luck to anyone who is currenlty having issues with their 7900GT's!

Anyone with a signature series based card able to get a hi res photo of the back of it? Might be worth seeing if theres any difference between them and a normal EVGA. May well be that its *just* a voltage boost to the core which has fixed the problem (although this is unlikely since people running over stock vGPU are still having issues) or that the regulation has been uprated to cope with the increased voltage....?

Quote:

---

Originally Posted by Roger_D25

Hey Guys,
Although there seems to be lots of threads in other forums this was one of the first ones I've read over here at extreme systems (I thought all you guys knew something none of us did), lol! Like many I have also had these problems, in fact I'm on my forth eVGA 7900GT RMA replacement. With the first 3 I began having the problems within 4 days of installing the card.

Then about 3 weeks ago eVGA announced that there was indeed a hardware based "Issue" that they had fixed by "Slightly Modifying" the replacment cards they were sending out? Of course they have been very vague about it the fix, where it is and what it is? So 1.5 weeks ago I filled out a special form they had on their message board for people who have been persistantly having the same issues with their 7900GT's, they said once the form was submited they would call/e-mail the persons back to take care of it. Well the next day I got a message from a Jacob Freeman who sent me a special "Cross-Shipment Authorization" form so that I could get my "Slightly Modified" replacments card first, and then ship out my third defective card within 30-days.

Then about 3 days ago I got my replacment which was the Signiture Series card with a modified BIOS so that the clockspeeds would match my 7900GT CO card (500/1500Mhz). Fingers crossed so far it was been working great even though I've been doing some serious gaming/benchmarking to push the card. This card does indeed run at 1.45v in 3D mode and 1.2v in 2d mode (checked with multi-meter). I'm not exaclty sure why they would do this except maybe that these cards have had a better track record so far with RMA's?

I realize that the SS card is fairly new in eVGA's line up but does anyone know if they actually do have a better track record than the other cards? When I put both my regular GT CO card and my new SS card side by side to compare the components they are certainly different in many ways. I'm no expert so I'm not sure what componets do what but I do know they are differnt in many ways. Well thanks for any help you can give guys and good luck to anyone who is currenlty having issues with their 7900GT's!

---

The changes to the SS board where the non SS boards have to be pencil modded or soldered to change the Vgpu voltage are already well communicated. Everything was already there on the PCB, but no components where installed.
With the newly installed mosfet switches, it is now possible to have a dynamic setting of te Vgpu by the GPU itself. Theoretically it is even possible to mount to components on boards not equiped with these parts and have your own SS fabrication.
But in all sense, the skills required to do this are beyond the average amateur.

My guess for the why is, most of the time your PC is in 2D, and the 1.2 Volt, applied to the GPU, let the GPU live much longer. Why should EVGA add extra components if 1.45 Volt all the time is just as good ?
So this could be one of the "Issues" that EVGA reported to extend the life of the board.

What I am really interessed in, can you find any differences around the Vmem regulator, the ISL6549, between the two boards that you have, and does the regulator plus one of the two mosfets next to the regulator becomes just as hot on your SS board??

Quote:

---

Originally Posted by Highland3r

The cards when they die exhibit the SAME symptoms as they do when the memories oveclocked too far. The vMem regs get MUCH hotter than the vGPU.
The GTX may use the "same" chips, BUT the regulation on the GTX is MUCH better than that of the GT. IF Nvidia used the same regulation on the GT as they did on the GTX then the GT's would simply be downclocked GTX's. They'd loose money.
The vMem regulation IS the issue on these boards. Not sure why a driver reload/reboot fixes the issue, sure theres someone with 1000* more knowledge on the subject out there.
The memory in 90% of the cases IS the issue with these cards.

<edit> As for the 2d/3d issue, the cards NOT loaded in 2d whereas it is in 3d (no s&*t sherlock...). Belive the issue is overloaded regs which overheat and crap out. Hence not occuring in 2d mode.... </edit>

---

Highlander,

What I dislike in your mail, is that you are just posing wild assumptions as being the thruth.
1) "When you overclock the mem, the symtoms are the same as when the card dies" ?? Where is the prove for that .
2) "The GTX has a MUCH better regulator for Vmem" ?? Is the regulator on the GT worse because it gets hotter? That would not be my definition of good and bad. The regulator on the GT is designed for 1320 Mhz. Overclocking the mem means more current demand, so the poor guy gets hotter. But is it not good because of that ? No way, it is probably an excelent regulator until the prove for the opposite is there. With proper cooling everything should be O.K.
Without proper cooling your GPU would also die, but is it a bad GPU because of that ??
3) "The memory is the cause of trouble in 90% of the cases" ?? Where is the prove?
By replacing coolbits with rivatuner, my board seems to function again.
Does Samsung memory not like Coolbits?

It is not my intention to piss you or anybody else off, but before pretending to have some black and white knowledge, you should be damned sure.

1. personal Experience... I've pushed GT's to far and they artifact. You get the same flashes/refresh issues on desktop when the rams pushed too far and FPS and scores drop. My XFX recently died. Guess what happened? It artifacted, refresh problems when switching 3d -> 2d and shock scores/fps dropped too..
2. If the regs on the GT's were as good as the GTX then they WOULDN'T overheat would they..? Yes the regulation is designed for stock running, but that ISN'T what I said.. The GTX is designed to run the ram at GTX speeds, and the GT at GT speeds...
3. See my above comment for #1 mate.

The reason IMHO Evga are using different 2d and 3d voltages is probably to keep heat down. I've not seen the superclocked cards personally, but I'd imagine they run the same coolers as the "normal" cards. 1.45v is a LOT for the stock cooler to cope with. Again personal experience has shown this :)

I'm not trying to make wild assumptions. I only say things like I see them.. If someone tell's me I'm wrong, and presents valid proof to backup their comments trust me I'll be the first to agree :)

Does replacing Coolbits with Rivatuner make it stable in games as well, or only benchable??

Best Regards :toast:

Quote:

---

Originally Posted by t024484

Highlander,

What I dislike in your mail, is that you are just posing wild assumptions as being the thruth.
1) "When you overclock the mem, the symtoms are the same as when the card dies" ?? Where is the prove for that .
2) "The GTX has a MUCH better regulator for Vmem" ?? Is the regulator on the GT worse because it gets hotter? That would not be my definition of good and bad. The regulator on the GT is designed for 1320 Mhz. Overclocking the mem means more current demand, so the poor guy gets hotter. But is it not good because of that ? No way, it is probably an excelent regulator until the prove for the opposite is there. With proper cooling everything should be O.K.
Without proper cooling your GPU would also die, but is it a bad GPU because of that ??
3) "The memory is the cause of trouble in 90% of the cases" ?? Where is the prove?
By replacing coolbits with rivatuner, my board seems to function again.
Does Samsung memory not like Coolbits?

It is not my intention to piss you or anybody else off, but before pretending to have some black and white knowledge, you should be damned sure.

---

Dude, you sound like your dead set against it being the memory on these cards that's causing the problem. I'm on my second card and it's acting up also. If I under clock my memory all runs good no artifacts so that is proof enough for me as when I try to run the card at stock or with oc on the memory it artifacts or crashes the system.:fact:

I'm not using coolbits either so no issue there. The card will do 580 on the core all stock but the memory won't even run it's rated speed any more without artifacting. X1900XT is looking better and better.:toast:

Quote:

---

Originally Posted by DTU_XaVier

Does replacing Coolbits with Rivatuner make it stable in games as well, or only benchable??

Best Regards :toast:

---

Everything I have tried including FEAR is running without any problems (so far), but the last thing I would like to suggest is that Riva Tuner is always better than Coolbits. It happens to be so in my case, but the reason why is written in the stars.

Quote:

---

Originally Posted by MisterFix

Dude, you sound like your dead set against it being the memory on these cards that's causing the problem. I'm on my second card and it's acting up also. If I under clock my memory all runs good no artifacts so that is proof enough for me as when I try to run the card at stock or with oc on the memory it artifacts or crashes the system.

I'm not using coolbits either so no issue there. The card will do 580 on the core all stock but the memory won't even run it's rated speed any more without artifacting. X1900XT is looking better and better.

---

I am absolutely not against any cause.
All I say is that this and similair Samsung gddr3 is used all over the world without any problems. Why should it be the cause of trouble in the 7900GT. Because of that it seems unlikely.
On the other hand, there is such a thing as a power supply that could malfunction, so far no prove of that, but it is already more likely than the Memory chips.
Next to that is the Clock generator. How well is this circuit designed, and how is the clock instructed to change the frequency, probably by the GPU, but we don't know.
A fact is that the memory is not producing its own clock, in fact the memory knows nothing about clocks although it should be clocked in the proper way. So when in an overclocking situation, like you describe, the memory gives up, is it the memory, the power supply or the clock generator. It can also be the GPU that is not able to read and write to the memory in the proper way or being not able to instruct the clock generator properly.
There are so many reasons, so without any further knowledge or hard facts, it is just guessing.


I think time will learn

Quote:

---

Originally Posted by t024484

A memory chip that malfuntions in 3D should also malfunctions in 2D, which is not the case here.
The 7900GTX has no problems with the same chips, etc, etc.

---

That is the logical conclusion, so I do agree. Especially when the same volt controll cuircuts are used in 2D and 3D.

I was just reaching because for my card it seems like memory problems.
I have also this strange ting, for HL2 based games I can overclock the mem, no problems. Running 3Dmark DeepFreeze og F.E.A.R the card crash every time. Need to go down to nVidia stock speeds (1320) to make it stable :confused:

I'm also agreeing that it's a heat issue, if they speced the IC for 1320, then this might be why OC'ed cards are having this issue? One would think that that there would be some headroom. I also think I remember reading something about some bad components comming out of china, and to stick with the japanese made ones. But this is just speculation on my part.

t024484 you seem the person with the firmest grasp of the situation and done som good investigations of the problem. What is you'r take?

Don't (personally) believe the Ram chips themselves are "going bad" its more a case of the regulation thats failing.

Quote:

---

Originally Posted by t024484

Everything I have tried including FEAR is running without any problems (so far), but the last thing I would like to suggest is that Riva Tuner is always better than Coolbits. It happens to be so in my case, but the reason why is written in the stars.


I am absolutely not against any cause.
All I say is that this and similair Samsung gddr3 is used all over the world without any problems. Why should it be the cause of trouble in the 7900GT. Because of that it seems unlikely.
On the other hand, there is such a thing as a power supply that could malfunction, so far no prove of that, but it is already more likely than the Memory chips.
Next to that is the Clock generator. How well is this circuit designed, and how is the clock instructed to change the frequency, probably by the GPU, but we don't know.
A fact is that the memory is not producing its own clock, in fact the memory knows nothing about clocks although it should be clocked in the proper way. So when in an overclocking situation, like you describe, the memory gives up, is it the memory, the power supply or the clock generator. It can also be the GPU that is not able to read and write to the memory in the proper way or being not able to instruct the clock generator properly.
There are so many reasons, so without any further knowledge or hard facts, it is just guessing.


I think time will learn

---

Hi guys,

I agree with t024484 mostly, though I think the other guys meant including the Vreg as well when they were stating that memory is the issue.
Still, I don't think GPU can not stand a voltage of at least 1.4V. (If added more I am not sure.) The main reason is that GTX GPUs are at 1.4V, and I haven't heard of any technology that can distinguish voltage tolerances between chips that are from the same fabrication process without permanently damaging them. Therefore, I think 7900GT GPUs can stand a voltage so long as GTX ones can stand it. So the question here is that is there a 7900GTX died because of some 1.5+ vmod?

I don't think the Vreg being hot is a sign of the cards' dying. Mine is hot from the beginning, even before I vmodded it. It stays at 640/800 well at least for now-- it's about 2 months.

So let's hope your card stays well from now on.

Quote:

---

Originally Posted by Lerun

That is the logical conclusion, so I do agree. Especially when the same volt controll cuircuts are used in 2D and 3D.

I was just reaching because for my card it seems like memory problems.
I have also this strange ting, for HL2 based games I can overclock the mem, no problems. Running 3Dmark DeepFreeze og F.E.A.R the card crash every time. Need to go down to nVidia stock speeds (1320) to make it stable :confused:

I'm also agreeing that it's a heat issue, if they speced the IC for 1320, then this might be why OC'ed cards are having this issue? One would think that that there would be some headroom. I also think I remember reading something about some bad components comming out of china, and to stick with the japanese made ones. But this is just speculation on my part.

t024484 you seem the person with the firmest grasp of the situation and done som good investigations of the problem. What is you'r take?

---

I have planned for this weekend to do some thorough testing on the Vmem regulator, and try to find out why the upper mosfet and the regulator are getting so hot.
If I find a solution I will let it know.

So far Im happy and running 1.55 VGpu and no other mods, Dont dare to do the vmem yet :)

Tried removing Coolbits today, and started playing F.E.A.R...
550/800 for clocks... Went fine the first 15-20 mins, then the core reset to nominal, though the game kept running fine... When I went back to Windows, the problem was back... So, I suppose I just oc'ed the core too high, will keep testing :)

Best Regards :toast:

It now turns out it must have been my core causing the problem... have removed Coolbits properly (forgot to remove the registry entry) and have played around with ATI-tool... the mem went all the way to 1800 before artifacting, but the core only got to ~530-540...
So removing Coolbits has removed my problem :)

Best Regards :toast:

Today I spent quite some time in measuring the performance of the Vmem regulator.
The conclusion? Everything works as it should.

The regulator is pulling some 25mA, independent of the load or frequency of the memory, so with the 12Volt supply, it consumes 1/3 watt.
With a thermal resistance of 100 C/W, this mean a temp rise of 30 C.
Everything is within the specifications and nothig to worry about.

The Voltage regulator for the GPU has a thermal resistance of only 50 C/W, thats why it does not get as hot as the Vmem regulator.

The upper mosfet, connected to the 12Volt, has a thermal resistance of 62 C/W.
I have measured with my osciloscope a rise and fall time of 10 nsec.
Switching frequency is 630 Khz.
With these parameters the switching losses when this fet is turned on are:
12(I+1)/300 , where I represents the current that is supplied to the Ram.
When this is 6A, this dissipation is 0.28 watt

The switching losses when the Fet is turned off are: 12(I-1)/300.
With the same 6A, this gives 0.20 watt.

Then there are losses to discharge the lower Fet.
This results in roughly 0.12Watt.

As a last dissipation factor, whe have the current flowing through the fet given the on resistance and the duty cycle. This dissipation is some 0.08 watt
In total whe end up with 0.28+0.20+0.12+0.08 = 0.68 Watt in an ideal world.
Let's give it some extra margin and assume it is 0.8 watt.
With the 62 C/W, this give a temp rise of 50 C.
At a room temp of 20C it results in 70C, enough to burn your fingers.

There happens to be nothing strange to he fact that the Mosfet gets so hot.
But with proper cooling, just a small heatsink measuring 20*20*20 mm. temp will never get above 40 C, so well under control.

Now the performance of the regulator: With loads varying wildly, it stays as stable as a rock. There is no current limit coming into action with all the possible memory loads.

So my conclusion can only be: apart from the cooling aspect, this voltage regulator is as good as you can possibly wish,solid as a rock and not sensitive to OCP or OVP.

t024484,
First of all thank you very much for taking the time to fully test the regulator, this is great info to know! Especially with all the talk about this card's mosfet temperatures being so high, it's nice to know their within spec! Not only that but it also narrows down the possible problems area's by rulling out the regulator section.

Also thank you for giving my your thoughts on the SS card I recenlty got. After looking at my old GT CO card it's clear that all the additional components on the SS could be added the GT CO without much trouble if your know what your doing! I just got out of work about an hour ago and it's quite late, otherwise I'd fully compare both my cards and answer your eariler questions about the VMEM regulator area differences. I've got tomorrow off so I'll do it then. I'll also try to take some close up shots of the VMEM regulator area on both cards so that you can compare them yourself as you'll notice much more than I will.

As far as the temps go I'll use my non-contact infrared thermometer to accuratly measure the temps of any points you want (regulator and mosfets). Thanks again to24484 for your help, talk to you tomorrow.

Something came up, was reading alot and ppl talking about the load dist of the 12V rails.

Even if both my 12V rails are rated for 20Amps this seems not to be enough. Problem with my PSU is I think the two 12V rails are devided between CPU and rest. So it may not be that easy to test without tapping into the cpu plug.

I was going to destribute load by using the 2xmolex to PCI-E converter to see if I could get a more stable system.

Can also someone else with more 12V rails try this?

We might be underestimating the load on the PSU with overclocking and all. Also manny PSU does not perform well if loads are not balanced between the rails (3.3, 5 and 12)

Quote:

---

Originally Posted by Lerun

I have also this strange ting, for HL2 based games I can overclock the mem, no problems. Running 3Dmark DeepFreeze og F.E.A.R the card crash every time. Need to go down to nVidia stock speeds (1320) to make it stable :confused:

---

Lerun, did you connect the 47Kohm resistor that I described here ?

http://www.xtremesystems.org/forums/...=94177&page=20

it is the last mail on this page.
In my case it removed the crashing completely.
Give it a try, and see what happens.

Quote:

---

Originally Posted by t024484

Lerun, did you connect the 47Kohm resistor that I described here ?

http://www.xtremesystems.org/forums/...=94177&page=20

it is the last mail on this page.
In my case it removed the crashing completely.
Give it a try, and see what happens.

---

Thought this applied for the core and not the memory. I'm only running the core at stock (500) before going further. If I encounter the problem when trying to go above 600 I will do as suggested.

Need to sort out why I'm having the artifact issue, if I down clock the mem to 1320 no probs. But at my stock 1500 artifacting appear.

Thx again t024484 you'r insight stears us all in the right direction :toast:

A small update from a non-electronics guy, who just wants his board to oc decently :) :
As I said yesterday, I have now found the core to be the problem, and I think it's some kind of heating issue I'm not picking up... will try remounting my VF-900 for safety... The mem runs grat 750, but the core won't even do 510 as far as I can see...

Best Regards :toast:

So I do have to eat my words. It's the PSU ?!!?

What realy puzzels me is that using any one of my two PCI-E connectors my card artifacts in 3DMark.

Read over at eVga some guy trying the 2xmolex to PCI-E converter cable to
distributing the load over two separate 12V rails. For me I did not think this was necessary or doable, because my 12vDc1 rail was only intended for the CPU and had a mother board connector on it. But out of options I desided to just test it, so I just connected the two molex connectors to the two different HD/DVD power cables comming out of the PSU (dropping one HD in the process).
Cranked up DeepFreeze in 3Dmark and waited, it ran once without artifacts.
I was like, just a fluke.... I ran it again, still no artifacts....:stick:
What is going on here :confused:

So it seems there is something to the load balansing thing, or the one HD I removed pushed the power consumption enough down to let the card run artifact free

For the first time I could also go to 1540 without insident....Now I realy can move on... perhaps to another PSU, but now I know what the problem is...

Thx ppl for all you'r good comments...this is a good day :woot:

:party3:

ARGHHH...spoke to quickly...they are back.

Going down to 1320 is the only way to get a clean run, *sigh*

Quote:

---

Originally Posted by Roger_D25

t024484,
First of all thank you very much for taking the time to fully test the regulator, this is great info to know! Especially with all the talk about this card's mosfet temperatures being so high, it's nice to know their within spec! Not only that but it also narrows down the possible problems area's by rulling out the regulator section.

Also thank you for giving my your thoughts on the SS card I recenlty got. After looking at my old GT CO card it's clear that all the additional components on the SS could be added the GT CO without much trouble if your know what your doing! I just got out of work about an hour ago and it's quite late, otherwise I'd fully compare both my cards and answer your eariler questions about the VMEM regulator area differences. I've got tomorrow off so I'll do it then. I'll also try to take some close up shots of the VMEM regulator area on both cards so that you can compare them yourself as you'll notice much more than I will.

As far as the temps go I'll use my non-contact infrared thermometer to accuratly measure the temps of any points you want (regulator and mosfets). Thanks again to24484 for your help, talk to you tomorrow.

---

Roger_D25
I am looking forward to seeing your high res pictures. Also the temps of the regulator and the mosfet are nice to compare with my calculations.
I hope you will find the time to respond.

I have an interesting twist to add to this mistery. I've recently been trying some of the newer drivers and I've had some success getting the card to run it's rated memory speeds. I'm using the 91.31 betas as we speak and they are by far the best and most stable. With all the other drivers I've tried I got massive artifacting in test 2 and 3 of 3dmark 03 and at the end the screen would be left blinking in and out.

I also could not run aquamark with out having it crash the system. Well 03 still does the blinking thing at the end but it's almost completely artifact free and aquamark runs fine now. All my other benchmarks now run perfectly up to 710/800. All my games, except for Oblivion are running great now with out artifacts. Oblivion has some minor pixel degradation in the upper right hand corner of the screen every now and then.

So it seems that some of the problems (maybe all) could turn out to be just a driver issue. t04484 you are right about there being many other things to consider in this and it would seem that my previuos assumtion was incorrect. :toast:

Quote:

---

Originally Posted by Mysterfix

I have an interesting twist to add to this mistery. I've recently been trying some of the newer drivers and I've had some success getting the card to run it's rated memory speeds. I'm using the 91.31 betas as we speak and they are by far the best and most stable. With all the other drivers I've tried I got massive artifacting in test 2 and 3 of 3dmark 03 and at the end the screen would be left blinking in and out.

I also could not run aquamark with out having it crash the system. Well 03 still does the blinking thing at the end but it's almost completely artifact free and aquamark runs fine now. All my other benchmarks now run perfectly up to 710/800. All my games, except for Oblivion are running great now with out artifacts. Oblivion has some minor pixel degradation in the upper right hand corner of the screen every now and then.

So it seems that some of the problems (maybe all) could turn out to be just a driver issue. t04484 you are right about there being many other things to consider in this and it would seem that my previuos assumtion was incorrect. :toast:

---

I got an asus en7900gt top with a 1.55v mod which is switchable. I game with stock voltage as atm cooling the gpu is a vf700cu and that's not enough imho for 1.55v. With stock v I can do 550/1600 all games and benches, BUT only with the drivers from the cdrom which shipped with the card. I upgraded drivers two times, and after both switches I found fear would freeze for seconds and sometimes oblivion would crash to the desktop. Went back to older drivers and the problems are gone. I'm still on those reference drivers, I might be missing some optimizations but atleast it doesn't crash.

P.s. don't ask my why or how this helped me, just letting you know it did :)

Yeah, I don't get it either, especially since the official drivers worked no problem when I first got the card but now they have issues. I can live with 03 not working for me as long as my games run fine.:cool:

Do you know if drivers without official 7900GT support might work?? AFAIK, nVidia hasn't given more than one driver with support...

Best Regards :toast:

They have beta drivers and official WHQL Certified drivers on there site.

http://www.nzone.com/object/nzone_do...etadriver.html

http://www.nvidia.com/object/winxp_2k_84.21.html

t024484,
Sorry it took so long to post these few pictures, also sorry about the quality! I did the best I could with my camera, by the way my digital camera is so old that it doesn't use a memory stick, it uses a 3.5" floppy disk that you actually put directly into the camera, lol! With that said the pictures don't look half that bad!

http://img106.imageshack.us/img106/7449/one9qj.th.jpg

http://img123.imageshack.us/img123/8177/two2xj.th.jpg

http://img215.imageshack.us/img215/5918/three8ov.th.jpg

http://img95.imageshack.us/img95/1140/four9dd.th.jpg

http://img95.imageshack.us/img95/8117/five6nl.th.jpg

http://img95.imageshack.us/img95/1478/six2bz.th.jpg

http://img138.imageshack.us/img138/6821/seven6bs.th.jpg

http://img138.imageshack.us/img138/8744/eight7sq.th.jpg

Hopefully you'll be able to know what your looking at from the pictures but if you have a hardtime getting your bearings just ask. I tried to take shots of the important components but if there is something in particular you want just ask and I'll try to get a better shot of it.

Quote:

---

Originally Posted by Mysterfix

They have beta drivers and official WHQL Certified drivers on there site.

http://www.nzone.com/object/nzone_do...etadriver.html

http://www.nvidia.com/object/winxp_2k_84.21.html

---

Both off which cuase fear to freeze up to 10 seconds and oblivion to crash to desktop :confused: But reference driver works great for me :stick:

I had the same problem with Oblivion but it wasn't driver related for me. It was the matroska codec pack (FFDshow) causing the game to crash, just had to adjust the settings so it didn't try to run when I started Oblivion.

Quote:

---

Originally Posted by Roger_D25

t024484,
Sorry it took so long to post these few pictures, also sorry about the quality! I did the best I could with my camera, by the way my digital camera is so old that it doesn't use a memory stick, it uses a 3.5" floppy disk that you actually put directly into the camera, lol! With that said the pictures don't look half that bad!

Hopefully you'll be able to know what your looking at from the pictures but if you have a hardtime getting your bearings just ask. I tried to take shots of the important components but if there is something in particular you want just ask and I'll try to get a better shot of it.

---

Your pictures are good enough to see that apart from the "Volt Switches", nothing, but really nothing seems to be changed.
What I cannot see are the values of the components, but most resistors have a funny coding anyhow, and the capacitors have no coding at all, so no picture in the world can bring us any further in that respect.
Thank you for taking the trouble.
I will further analyse the switch harware, and see if an easy DIY solution is possible.

My 7900Gt "co" is dying, i get artifacts in deep freeze and many games such as oblivion...but i tried what Lerun did, i connected the card with a molex adapter...the first run in 3dmark went fine...but i think it won't work....

I analysed the extra components on the EVGA SS board, that are used for Volt Switching.
There are 4 possible settings of the Voltage, being:
1) 1.2 Volt
2) 1.3 Volt
3) 1.45 Volt
4) 1.55 volt.

Since I do not have a EVGA SS Bios, I cannot see if option 4 will be possible.
Obviously EVGA is using the 1.2 and 1.45 Volt settings.
It is very easy to change this 1.45 Volt into 1.55 Volt, while leaving the 1.2 Volt for what it is. See picture below, the red line.
Attachment 48484

With only 3 semiconductors, instead of the extra 7 semiconductors that EVGA used, will it be possible to have a DIY Volt Switch feature.

What I need is the EVGA SS BIOS.
Roger_D25, could you please be so nice and make your BIOS available.
I will modify my board after having received the proper bios and tell what happened.

Don't know if anyone cares but I crushed a x1900xtx with the Zalman vf900 but it wasn't visable. Exact same symptoms as some people are having here. It only got worse. Nice thing is I got an RMA on that.

Cheers.

For those of you whose memory wont go past stock without blackouts etc...

Do you have cooling on the back of your cards on the hotspot?

IF SO, is it also touching the memory frequency chip? (The long black chip next to the memory vmod resisitor). If so, MAKE SURE IT IS NOT. That chip doesnt like being sinked.

Quote:

---

Originally Posted by t024484

I analysed the extra components on the EVGA SS board, that are used for Volt Switching.
There are 4 possible settings of the Voltage, being:
1) 1.2 Volt
2) 1.3 Volt
3) 1.45 Volt
4) 1.55 volt.

Since I do not have a EVGA SS Bios, I cannot see if option 4 will be possible.
Obviously EVGA is using the 1.2 and 1.45 Volt settings.
It is very easy to change this 1.45 Volt into 1.55 Volt, while leaving the 1.2 Volt for what it is. See picture below, the red line.
Attachment 48484

With only 3 semiconductors, instead of the extra 7 semiconductors that EVGA used, will it be possible to have a DIY Volt Switch feature.

What I need is the EVGA SS BIOS.
Roger_D25, could you please be so nice and make your BIOS available.
I will modify my board after having received the proper bios and tell what happened.

---

It looks like the picture I posted of my SS card? Now I realize you don't have a SS card so you havn't been able to try this mod but do you think it's safe to do so t024484? I'll give it a go and throw a meter on it to see if it worked or not? I know you already posted this mod and that it might work but I don't want to take any chances with my newest RMA card, lol! Thanks man

Quote:

---

Originally Posted by Roger_D25

It looks like the picture I posted of my SS card? Now I realize you don't have a SS card so you havn't been able to try this mod but do you think it's safe to do so t024484? I'll give it a go and throw a meter on it to see if it worked or not? I know you already posted this mod and that it might work but I don't want to take any chances with my newest RMA card, lol! Thanks man

---

Although I have no SS board, I am 100% confdent that this 1.55Volt mod is O.K. so don't worry.

this might be stupid, but mabey if its really up to the gpu, mabey these cards need a "burn-in" period, keeping them stock (nv 450mhz) for few weeks and then try OCing, mabey ill try that with mine when it comes back from rma, even though i had a conductive pen sent to me from halp way around the world.

Alright I'll give it a go and post back when done with results. I'll make sure to take meter readings to make sure the mod worked! Thanks again t024484

In another forum, somebody described the positive effect he noticed after having the board cleaned, the maximum frequencies went up with large steps.
The suggestion was that finger smear and debris where causing parasitic effects.
To make a long story short, I cleaned my board with special PCB cleaner, to remove all flux deposits, and then with a general board cleaner.
Guess what, not one single Mhz increase of the Mem/GPU, the effect is simply unnoticeable.

I must say I'm not suprised by these findings, good of you to test it all the same! I've also read posts from people who described similar results from a major PCB cleaning. I would imagine the only way to get positive results would be from someone who had some type of problem to begin with (major flux deposits, etc...).