FX5900XT Vmod, anyone?

**TodB** · 02-24-2004, 03:21 PM

Is there somebody with a FX5900XT that knows the Vmods?

In particular those with the Intersil ISL6522..... I got one Gigabyte FX5900XT, using two ISL6522.... I think for both memory and GPU...

Any info? at least what pot range? 200k, 100k, 50k?

**TodB** · 02-25-2004, 10:42 AM

Not a single person with a Vmodded 5900XT?!?

**Garrett** · 02-26-2004, 12:54 PM

http://www.ocforums.com/archive/thread/267604-1.html
This is an interesting thread of a guy who obviously vmodded his 5900XT and he did even manage to fry his card in the process

The vmod on the GPU is on the ISL chip. Pin 5 to ground. At 15K Ohms the voltage increases from the stock setting of 1.45 to 1.5v. Ran it up to 7.54K Ohms and got 1.55v. This allowed me to bench at 525/976 on 2001 and 520/976 on 2003. Cooling has still not been modded as of yet so I did not take it any farther. Ran the mod on the 6012 chip however got heavy artifacting even though it would run up to 525/1009. This indicates to me (at least as of this time) that the ram is not up to the task of running at those speeds. Without the vmod with the card at 525/990 it would kick down to the slower speeds seen in 2D. For now 976 will have to suffice and I will not leave the 6012 mod in place. Now for the results.

Ran the voltage up to 1.65v on the GPU. This achieved 535/976. Not bad for the 5900XT. Brought up 2003 and started running it. Scores where looking really good however I was somewhat alarmed when about half way through the artifact free run, there was a spectacular ball of flame and sparks that came from the vid card. We are talking a rather large ball of fire. Really brightened up the room it did. One of the benefits of testing at night is the spectacular fire works show. For those unaware, this really is not a desired effect. I now have a very burned, eight leg chip (id unknown due to the numbers being burned off), located next to the ram, towards the end of the card on the front side. Seems that though the GPU can handle the voltage, there appears to be a circuit that can not on the 5900xt. Too bad as the in the first test, when the fighter is firing, the fps got up to 1,000. Would have been a good run however it needed to complete it without frying the card.

At any rate no further damage done to the computer and presently have a backup 4200 in it.

I hope this helps you, and me too, because yes, I'm looking for a GPU Vmod too for my Club3D 5900XT

**Mod_Aap** · 02-26-2004, 01:07 PM

Here it is:
http://www.ocforums.com/vb/vb/showth...highlight=volt
Have fun

**Garrett** · 02-26-2004, 01:09 PM

http://www.ocforums.com/showthread.p...97#post2495997 is the "original" thread on the pieces I quoted, correct me if I'm wrong

**TodB** · 02-27-2004, 01:42 PM

Well that info is something, but...... not enough... that guy says some, but I need more info.... measuring points, etc...

Send him a PM, we'll see...

**Hud stromar** · 02-28-2004, 06:28 AM

I'm looking for that Volt mod too.

Here are some pictures of the card, how it looks
Front:

Back:

I think that all the important IC's are marked with red numbers.

IIRC the nuber 1 and 2 on the back of the card are Intersil's ISL6522

If anybody knows more than I do, the help would be more than welcome

**Bra!nFreeZe^** · 03-02-2004, 01:44 PM

Im getting one this thursday so Ill check it out

**XanderF** · 03-02-2004, 08:51 PM

Awesome, let us know what you find!

I have some ramsinks on order and another radiator for my WC setup. I figure I'll probably be taking the whole thing apart for 'upgrades' again this weekend, and a workable vMod on the graphics card would be awesome!

(I had to pull the work I did to date - didn't seem to offer any additional speed on the little resistence I dropped, and no way to read the voltage, so I didn't want to push it)

That auto-slowdown thing is really pissing me off, though. No way to know what the real, running, clock is!

Is there any program that, while running complicated 3d tests, could display the current core clock in some corner of the screen or something?

nVidia's Coolbits overclock control SEEMS to know when it is 'too far' on memory. But, it's allowing core clocks that, in use, it decides it needs to reduce. That's kinda annoying, I want to know what my card's limits REALLY are!

(Right now I'm running 485/780 on it. 800 was possible on the mem before removing the stock HSF to put on a waterblock, I imagine it will be again when I add some ramsinks and a card cooler blowing at it. Still, sometimes the core clock seems to drop.)

**Bra!nFreeZe^** · 03-03-2004, 03:26 AM

Dont you think that forcing older dets to work on the card would fix the auto-slowdown thingie ?

**XanderF** · 03-03-2004, 02:59 PM

Perhaps, but the reason I sold my 9800 for this card was that I prefer nVidia's drivers a lot.

Especially since I've tried the 56.56, I've been hooked. I LOVE that application profile application through auto-detection. I'm sure ATI will copy this - at least, I hope, lest my next upgrade be a very one-sided decision.

I think I used the 45.23 before with good effect. That, at least, had FSAA that worked in 'Raven Shield' - the 56.56 breaks that. The official 53.03s (current WHQL) just break WAY too many games for me to use.

What drivers would you recommend? I could certainly try them!

(As an aside, I have no way of knowing....for sure....that this is what is happening. It just seems during very intense 3d scenes that my video card just stops for a while - say, 30 seconds or so - and when it starts up again the framerate is much lower. From what I understand, that's a symptom of the card auto-downclocking. During cool periods of the day, it doesn't seem to happen - and, if I run it at 475 instead of 485, it seems okay as well.)

**OperativeSix** · 03-04-2004, 10:30 AM

Originally posted by XanderF

(As an aside, I have no way of knowing....for sure....that this is what is happening. It just seems during very intense 3d scenes that my video card just stops for a while - say, 30 seconds or so - and when it starts up again the framerate is much lower. From what I understand, that's a symptom of the card auto-downclocking. During cool periods of the day, it doesn't seem to happen - and, if I run it at 475 instead of 485, it seems okay as well.)

Textbook description of the 5900 cards throttling back the core speeds. I'm curious as to how it determines the scale-back speed, though. I know it doesn't default back to 300mhz (like in 2D mode), as when I clock the core at 500mhz with poor cooling, it will throttle to ~370mhz. Seeing as it clocks from 400mhz to 300mhz default, it could very well just be 75% of the default speed. Perhaps this could be another way around the throttle, by just setting the clock speed 33% above what you want it to be?

**Bra!nFreeZe^** · 03-04-2004, 02:06 PM

Originally posted by OperativeSix
Textbook description of the 5900 cards throttling back the core speeds. I'm curious as to how it determines the scale-back speed, though. I know it doesn't default back to 300mhz (like in 2D mode), as when I clock the core at 500mhz with poor cooling, it will throttle to ~370mhz. Seeing as it clocks from 400mhz to 300mhz default, it could very well just be 75% of the default speed. Perhaps this could be another way around the throttle, by just setting the clock speed 33% above what you want it to be?

Hmmm that might be it ! until now my card havent throttled back yet and im running my 5900XT at 480mhz and 781mhz

**TodB** · 03-05-2004, 12:40 PM

Weird..... I checked all the capacitors on my GB FX5900XT and the close ones showed around 2.5V..... I got 2 side by side capacitors, both measuring 2.53V.... ain't that quite low for a Vmem?!?

The Vcore showed 1.43V...

**Bra!nFreeZe^** · 03-05-2004, 12:48 PM

Can you take some pics as where to measure the voltages ?

**TodB** · 03-05-2004, 12:54 PM

Well... no problems.... I'm sure about the Vcore, but the Vdimm is on hold.... I'm going to snap it now, so we can discuss about....

**Bra!nFreeZe^** · 03-05-2004, 12:56 PM

Allright Im looking forward to seeing it

**TodB** · 03-05-2004, 03:23 PM

OK, here's the GPU Voltage reading point.... will check the DDR reading point tomorrow

**Bra!nFreeZe^** · 03-06-2004, 04:28 AM

Thx d00d! btw have you vmodded it yet ?

**TodB** · 03-06-2004, 07:59 AM

Well... yeah..... the 3D Vgpu jumped from 1.43V to 1.59V and the GPU freq jumped from 480MHz to 535MHz... that with the present cooling, of course

**Bra!nFreeZe^** · 03-06-2004, 08:01 AM

Nice I need details right now! mine does 500mhz stock gpu cooling...and I have a Volcano 12 right here that just needs to be mounted

**TodB** · 03-06-2004, 09:25 AM

Well the second ISL6522 chip on my card seems to control the Vddq voltage.... I'm not 100% sure, but I think there's no way that 2.8ns memory will run 800MHz/2.5V....

I'm left with one last chip on the back of the card, will test it later..... if I find an info about....

**XanderF** · 03-06-2004, 06:05 PM

Excellant, and be sure to post pics of where to mod and what you did!

I think I had made some headware, but it was a false start. I'll be pulling my card out again next week to add ramsinks, and I'd like to vMod it while out.

**Bra!nFreeZe^** · 03-07-2004, 12:41 AM

TodB cant you post the vgpu mod so far ?

**macci** · 03-07-2004, 02:22 AM

Anyone got problems flashing 5950 bios on these 5900xt cards??
I've got the albatron 5900xt model (runs 3dmark03 at 525/803 with stock cooler 1.59V Vgpu) and flashed the leadtek 5950 bios in there. It boots up fine and reads 5950 in the bootup but WinXP is all phucked. 4bit colors etc

at some point it gave some 'no enough resources' error. Anyone seen this? how to fix it??

**macci** · 03-07-2004, 02:34 AM

Vgpu mod for 5900XT:

Connect that pin to GND via VR. 3.76kOhm gives 1.6V on my card.

**macci** · 03-07-2004, 02:37 AM

I tried the Vmem mod too from 2.86V to 3.3V and it didn't help anything at all btw (its the second ISL pin 5 to GND).

**Bra!nFreeZe^** · 03-07-2004, 02:37 AM

Hmmmm I havent tried that yet....but thats mainly because my mem only runs at 770 but my core is good for 500mhz stock vgpu n' stock cooler.....Macci I was wondering If you couldnt post a pic of the vmem mod? I would greatly appreciate it...I think that you problem is caused by the mem speed on the 5950 cards, because the run at 850mhz dont they ? have you tried clocking the mem down ?

**macci** · 03-07-2004, 05:20 AM

5950s run at 950 mem IIRC the 5900ultra runs 850. Ive tried both of those BIOSes and neither of em works. I just get some 'device cannot find resources' error in winxp control panel and the desktop screen is useing 4bit colors

Flash back to albatron 5900XT and it works normally.
Rivatuner wont see the card at all so no way to lower the clockspeeds.
I've read that people w/ LEadtek 5900XT (it has 2.8ns hynix just like this card) have succesfully flashed to 5950 and are able to run the RAM at way above 900MHz.

**Bra!nFreeZe^** · 03-07-2004, 05:29 AM

My card has 2.8NS sammy mem...maybe the leadtek cards have more relaxed timings ? btw could you be so kind and post a pic of the mem vmod ?

**TodB** · 03-07-2004, 06:19 AM

Originally posted by macci
I tried the Vmem mod too from 2.86V to 3.3V and it didn't help anything at all btw (its the second ISL pin 5 to GND).

Man, I was almost certain that there's something foooking wrong with that... got the mod too, but almost no improvement at all....

But then again, where do you measure the Vdimm? Cuz the closest I can get with that Gigabyte is around 2.53V... with the mod I'm getting it up to 2.81V.... and that helps for around 20MHz or so...

**Bra!nFreeZe^** · 03-07-2004, 06:52 AM

Wanna give me some info on that mod ? :P

**Bra!nFreeZe^** · 03-07-2004, 07:46 AM

Btw I have completely forget how to measure the capacitators...should I measure on both legs or should I measure the + pin and ground ?

**HaLDoL** · 03-07-2004, 09:50 AM

I have 2 Point of View cards, one with a red pcb does 530/777 on stock cooling (it has samsung 2.8ns memory) and the other one has a black pcb and it does 530/945 stock (it has 2.2ns Hynix memory).

**Bra!nFreeZe^** · 03-07-2004, 10:22 AM

I also have the one with a red pcb...which unfortunately seems to be sucky :P

**XanderF** · 03-07-2004, 12:31 PM

I've read that people w/ LEadtek 5900XT (it has 2.8ns hynix just like this card) have succesfully flashed to 5950 and are able to run the RAM at way above 900MHz.

That's the "lazy man's vmod". Over on the ocforums, IIRC, someone tested the voltage before and after BIOS flashes.

Apparently, the 5950 BIOS does provide about .2v more to core and mem. (Harder to test, but evident by initial lower scores at the same clock and higher possible clocks, is that the 5950 BIOS *also* reduces timings on the memory. Both things that lead to much-higher-than-anticipated memory clocks.)

The thing about these cards is that the voltage is 'software' controlled. For 'safe', '2d', and '3d' modes, it offers 3 different voltage levels - and, as noted - a BIOS flash can change them.

It seems pretty obvious someone could write a program to access that directly from Windows, if they were so inclined.

Connect that pin to GND via VR. 3.76kOhm gives 1.6V on my card.

Pin 7 on that chip is ground, right?

**XanderF** · 03-07-2004, 12:40 PM

I tried the Vmem mod too from 2.86V to 3.3V and it didn't help anything at all btw (its the second ISL pin 5 to GND).

What resistance did you use for this? And what voltage is 'stock'?

These are the pins I tried to use! According to this document, for the ISL chip, pin 5 is feedback (as you are proving) and pin 7 is ground.

Yet, stock (unmodded), I measured .73 kOhm resistance between these two points! Shouldn't the FB pin to ground pin be 0.0 resistance?

**OperativeSix** · 03-07-2004, 09:33 PM

Have you tried editing the BIOS's at all to change vendor ID's, or other such info macci? Hardclocking the card back down to XT speeds might fix something.

**Bra!nFreeZe^** · 03-07-2004, 10:29 PM

I was thinking....doesnt the 5950 have 256mb of mem ? and the FX5900Xt only have 128mb couldnt this be the problem ? because when ppl with the 9800pros flash to an 9800XT bios they get alot of problems because of that ?

**XanderF** · 03-07-2004, 10:35 PM

doesnt the 5950 have 256mb of mem ? and the FX5900Xt only have 128mb couldnt this be the problem

No, the BIOS on the FX cards doesn't control how much memory the card is looking for. It's almost PC-like: on bootup, it detects how much ram is 'installed' and uses that for the card.

**Bra!nFreeZe^** · 03-07-2004, 10:37 PM

Oh allright....btw when measuring the Vgpu on the card...should i only hook one of the wires on my multimeter up to the capacitator and one to ground ?

**macci** · 03-07-2004, 11:42 PM

I tried bios editing but the only tool Ive got (NV BIOS editor) cannot mod the clocks speeds on FX5900 series. Anyone got links to better bios editing tools/modded FX5900 bios files?

XanderF, Yes pin 7 is GND there. My card was at 2.86V stock for Vmem. I used a 15kOhm VR for starters and lowered the value until it was at 3.3V Vmem - which didn't help the RAM oc at all.
The original resistance from pin 5 to GND is around 0.7kOhm and once we solder a VR in parallel w/ that the resistance gets lower and voltage goes up.

**TodB** · 03-08-2004, 03:05 AM

Originally posted by macci
My card was at 2.86V stock for Vmem.

Man, you didn't say anything about the Vdimm reading point??

**macci** · 03-08-2004, 03:27 AM

Basically any SMD cap near the memchips

**TodB** · 03-08-2004, 03:37 AM

Didn't think of it that way... hmmmmm...

Just for the record - those two are showing some voltage change when I'm lowerin' the resistance on the second ISL chip.... can you check them too? Just for an opinion....
I'll check the SMDs right away....

**TodB** · 03-08-2004, 03:48 AM

Damn, I forgot the pic:

**Bra!nFreeZe^** · 03-08-2004, 05:03 AM

Oh allright....btw when measuring the Vgpu on the card...should i only hook one of the wires on my multimeter up to the capacitator and one to ground ?

**TodB** · 03-08-2004, 05:39 AM

Yes... one of the to ground (black cable on the MOLEX conectors) and the other in the desired spot...

**Bra!nFreeZe^** · 03-08-2004, 06:16 AM

Alright thx....could you post a pic of the vmem mod ?

**XanderF** · 03-08-2004, 11:12 AM

XanderF, Yes pin 7 is GND there. My card was at 2.86V stock for Vmem. I used a 15kOhm VR for starters and lowered the value until it was at 3.3V Vmem - which didn't help the RAM oc at all.
The original resistance from pin 5 to GND is around 0.7kOhm and once we solder a VR in parallel w/ that the resistance gets lower and voltage goes up.

Right, so I was doing the right thing.

Probably my resistor was too high, though. I'm use to ATI cards that seem to take 13kOhm and up, so I 'made' a 20kOhm pots by soldering together a 10kOhm pots and a 10kOhm resistor.

Downside, of course, is that I can't do less than 10kOhm that way.

What resistance are you using on it now? If less than 10, I'll just use the 10kOhm pots on its own for both vMods. Easy enough to do.

**Garrett** · 03-08-2004, 11:44 AM

Originally posted by XanderF
Yet, stock (unmodded), I measured .73 kOhm resistance between these two points! Shouldn't the FB pin to ground pin be 0.0 resistance?

I don't hope so... it would fry the card... it would be the same as to CONNECT these 2 pins

Anyway... what VR should I get for the VGPU mod? 10K? 5K?
I'm about to tear off the HS and watercool this sucka so if I can vmod it at the same time it would just be as easy, eh?

**Bra!nFreeZe^** · 03-08-2004, 11:48 AM

Damn I cant wait to vmod this sucker :P

**Bra!nFreeZe^** · 03-09-2004, 10:51 AM

Hey Macci how much do you think that this card can score in 3dmark01 ?

**Garrett** · 03-09-2004, 12:33 PM

I'm not Macci but why don't you try the Futuremark Project Search & Compare option

By the way guys, if I choose to voltmod the GPU, will there be another chip like a voltregulator or something that will get hotter too?
I can put a small heatsink on about any chip so IF that's necessary please tell me which one it is...

**Bra!nFreeZe^** · 03-10-2004, 07:55 AM

I tried Vmodding mine yesterday and it died....first I added a molex connecter from an old broken psu to check the vgpu...booted up and it worked fine reported 1.23 while in 2d mode and 1.43 in 3d mode....I turned of my pc and added the vr to the pin on the isl chip and grounded it on the black wire from the molex connector on the card, the exact same grounding point as the vgpu monitor and I plugged the card back in...making sure that all connections was OK, turned on the pc....the card was making some weird noises and the fan wasnt running and my multimeter was going nuts! and I double checked that my VR was at 0ohm.....just died! well its rma time, luckily I did the mod really clean...so Ill try again as soon as I get a new card...btw would you mind posting some pics of your cards modded ? , so that I have the possibility to check what I did wrong

**Garrett** · 03-10-2004, 08:39 AM

Originally posted by Bra!nFreeZe^
I tried Vmodding mine yesterday and it died....first I added a molex connecter from an old broken psu to check the vgpu...booted up and it worked fine reported 1.23 while in 2d mode and 1.43 in 3d mode....I turned of my pc and added the vr to the pin on the isl chip and grounded it on the black wire from the molex connector on the card, the exact same grounding point as the vgpu monitor and I plugged the card back in...making sure that all connections was OK, turned on the pc....the card was making some weird noises and the fan wasnt running and my multimeter was going nuts! and I double checked that my VR was at 0ohm.....just died! well its rma time, luckily I did the mod really clean...so Ill try again as soon as I get a new card...btw would you mind posting some pics of your cards modded ? , so that I have the possibility to check what I did wrong

You tried to voltmod your card with a VR set to 0 ohm? OMG!!!

If that's what you did it's no surprise it died, you need to set the VR to its maximum and SLOWLY reduce the resistance, thus upping the voltage... NEVER start at 0 ohm!!

**Bra!nFreeZe^** · 03-10-2004, 08:49 AM

Damn I misunderstood!

some vmods you have to raise the resistance so the vreg thinks that it doesnt supply enough voltage!! well Ill remember that the next time :P

**Garrett** · 03-12-2004, 01:54 PM

Well I voltmodded it too... 3.68Kohm and a nice 1.63v in 3D mode...

Hmmm a pretty big increase in core speed if you ask me...
478 before the mod, and 542 after!!

**TodB** · 03-12-2004, 04:03 PM

Originally posted by Bra!nFreeZe^
Damn I misunderstood! some vmods you have to raise the resistance so the vreg thinks that it doesnt supply enough voltage!! well Ill remember that the next time :P

Well it's always from MAX to MIN and never the other way around.... like that you gave your GPU like... u-u-uhm.....around 3V....

**Bra!nFreeZe^** · 03-12-2004, 11:31 PM

No wonder it died then

well Im getting a new one next week and if Im lucky...it comes along with a shuttle SN45G

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