Who did that ? i'm quite surprised :confused:Quote:
Originally Posted by flytek
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Who did that ? i'm quite surprised :confused:Quote:
Originally Posted by flytek
this poor guy: http://www.xtremesystems.org/forums/...9&postcount=21Quote:
Originally Posted by Ebola
i have also seen at least two revisions of the vmem vreg ic on 7900gt's.
so maybe they figured there was a problem with the earlier cards and changed it.
i'm not convinced iether way yet but it seems reasonable to treat the vmem mod with caution for the moment.
does this card drive anyone else crazy? with conductive ink mods i was getting bad flashing screen problems, so i did the 'resistor k' mod as well as replacing 'j' for 1.5v. still having a lot of problems with this card, although it's clocking very well when it works. i am not looking forward to replacing resistors 'i' or 'h' so was wondering if anyone had any suggestions?
Step 1 & 2 done, can someone pls tell me if the line i've drawn in Aqua (attatched pic) is the closest ground point for 1.6v mod?
Will be using ink pen to draw line.
Thanks
C-BuZz
The ink will also come off really easy if you use a fine point sewing needle and magnify glass.Quote:
Originally Posted by quijonsith
Ok, 1.6vmod done. 800/500 artifact free after a few 06 runs. 1.7v seems unstable & keeps crashing my system in full 3D. I can run ATITool 830 core ok but crashing in 06.
Any ideas?
C-BuZz
somewhere in one of these threads i read you should use the Vmem mod to keep your core clock stable. So if you havent done the Vmem mod, you may want to try that avenue to see if it gets 1.7V stable. It could also be a heat issue as well...
I've done the vmem mod.Quote:
Originally Posted by Haltech
The card is now loading @ 1c so it's definately not a heat issue :)
Somthing interesting, If I lower mem I can pass 06 @ 825/450 1.7v.
Anything higher it just straight blackscreen & have to reboot. Whereas I use 1.6v on core & I can do 800/500 runs no prob :confused:
C-BuZz
Sounds like a power regulation problem, these cards have their limits using the very basic power reg they have :)Quote:
Originally Posted by C-BuZz
Did you already try to increase the switching frequency? (resistor K)Quote:
Originally Posted by C-BuZz
Your problem seems to be a current limit, either in the Vgpu or in the Vmem supply.
My guess is that it is the Vgpu supply.
To change the current limit in the Vgpu supply, change resistor H from 3k5 to 6k8.
Step 2 in the drawing that you showed does not remove the current protection as mentioned already at the beginning of this thread.
BTW the 825Mhz that you can get with your board is unbelievable. What manufacturer and type of board do you have ?
If this does not help you, we can change the current limit of your Vmem supply.
sorry not to sure what you mean there, 3k5 to 6k8? I removed & replaced the resistor with a 51K resistor as described in step 1, is that suitable? & I removed both current protection resistors. Then I used the cunductive ink to ground for 1.7vcore. Was crashing in 3D after about 3secs.Quote:
Originally Posted by t024484
Are you saying that Step 2 pictured above does not remove Over current protection??
1.6vcore seems quite stable.
I going to have to try a new power supply as I beleive it could possibly be my crap psu giving me issues.
Here is my latest run with 1.6vcore
http://forums.overclockers.com.au/sh...&postcount=272
Card is Forsa.
C-BuZz
Step 1 with 51K is O.K.Quote:
Originally Posted by C-BuZz
Step 2 in the picture does not remove OCP.
Look at the first posting in this thread, and you will understand what I said.
Great, so i've removed 2 load balancing resistors for no reason :slapass: nice 1 vrzone..Quote:
Originally Posted by t024484
ok power supply has now been ruled out so its definately a problem with the card.
I've done some further testing & 1.6v works fine up to around 800 core very stable & no artifacts. Any volotage over 1.6v on the core & it dies in 3D after 3seconds. I can boot into Windows no prob @ 1.7vcore, but run 3D & it dies.
SO, it looks like the OCP Resistor "H" is kicking in after all. Could I use a pencil on this to increase the resistance?
Thx for your help :)
C-BuZz
Resistor "K" was the key to my problems.
I penciled it & got this. 1.7v on the core, Totally artifact free.
C-BuZz
Well I didnt come this far not to try 1.75v on the core :) Finally got the card loading in the positives.. around +3/5c. Think my modified Vapo is beginning to struggle a little, as evap temps are around -13c when fully loaded.
This run artifact free. I can forsee 850/860mhz core benchable no probs :) I was hoping for 100% clock but I guess I cant have everything..
I think the card is becomming quite bottlenecked by cpu.
C-BuZz
C-BuZz, how long are you running the artifact scanner? I've had plenty of times that I got no artifacts for ten minutes only to let it go a little longer and have it burst into artifact central. I run it for atleast 25min personally to be sure it's good. Also, what cooling are you using and what are your temps?
I've found artifacts behave differently when temps are in the negatives & the core doesnt get the chance to fully heat up. I have run the scanner for 1hr before & they where no different to a 10 second scan.Quote:
Originally Posted by quijonsith
With a normal heatsink/fan setup they usually wont show straight away/or they get worse as the card becomes hotter & the core heats up.
With the gpu running @ these speeds, the core temps are +5c MAX so the artifacts wont get any worse over time as the core can not get any hotter. Idle core I think it drops to around -10/-15c.
I have completely rebuilt a vapochill PE for the task :) Although i'm beginning to think it's not quite up to it heh..
C-BuZz
Ah, you got extreme cooling and then some :) I am using a vf900cu myself. Even when my temps were below 60c I have had artifacts show up after 10min on some speeds until I lowered the clock slightly. Then it makes it to 25min and I call it good. Nice to see someone pushing the limits past 1.7v.
Dunno about extreme, but it's a lot better than what I had heh...Quote:
Originally Posted by quijonsith
Cards behave a lot differently @ very low temps :)
I could barely squeeze 700mhz out of the core with my ghetto heatsink mod & 1.55vmod. But when I strapped my Vapo to it I was doing 780mhz runs with 1.55vcore easy :)
Considering pumping 1.8v through it, but i'd crack it if she died :D
C-BuZz
Had to try it lol, but she didnt like 1.8vcore to much. Was exhibiting similar problems as before, however 3D mark would just close to desktop. Wouldnt actually crash the whole system like before.
That was @ 860 core heh..
1.75vcore seems like a winner.
C-BuZz
oh yeah definitely. lower temps result in higher stable clock speeds in general. There's atleast a 15mhz difference between my a/c working so that the core stays at or below 60c, and when my a/c doesn't work and the card can get to 65 or in some cases 68 (this is using atitool to heat er up of course; in game temps are much better).Quote:
Originally Posted by C-BuZz
since i'm on air cooling I can use my temps as a guideline for how much voltage I can push. With vapochill (and IMO it is extreme cooling) you really only have your own guts as judgement.
On the upside, had your card died you would have provided the entire 7900gt vmod community with the kill zone voltage for the core :D....a very expensive lesson it would've been. Glad your card survived.
hehe me to. I redid the 1.8v mod & did some further testing @ 860core. This time crashing to desktop after about 30sec of running 3D. Seems similar to last problem. I'll try pencil the resistor a bit more & see how we go.Quote:
Originally Posted by quijonsith
C-BuZz
Congrats C-BuZz :clap:Quote:
Originally Posted by C-BuZz
I never thought I would ever see such a high OC :toast: :toast:
wow.. (on 1.8v w/ 860 core) impressive!!
Please read the first posting of this thread.Quote:
Originally Posted by xit
I have read this thread and numerous others on the web.Quote:
Originally Posted by t024484
My question is posed because of conflicting information, and I appreciate knowledge from other people who have tried it.
I note your detailed image, but if it WAS perfectly clear I wouldn't be posting a question now...
Please and thank you. :slapass:
What exactly is conflicting, and what is not perfectly clear?Quote:
Originally Posted by xit
crap. I think I worked it out.Quote:
Originally Posted by t024484
Soz. I was confused by the references to 1.7v, but now realise it is if the 5k resistor is in place only.
Hmm, I have a wierd problem. I got a new 7900GT to play with, and so far it doesn't seem to be as good as my first one. The core goes high, but the memory won't go passed 830 or so.
Ok, the problem is, my resister labeled "K" in the first post of this thread, seems to not be working. I checked it with my meter, and there is nothing there. I made sure I cleaned both solder pads at each end of the resistor incase there was some film on there keeping me from getting good contact. Still nothing at all.
So what kind of problems could this cause?
Also, I checked the voltage to my memory and it seems to be at .800v. I know that can't be right, but i'm pretty sure I checked it at the right place. I shaded the resistor to up the vmem like the vrzone site says, and checked again at still .800 and the memory didn't seem to overclock anymore than before.
The card will run 730/830 with a 40mhz delta pretty well, but the scores are low compared to my other card. I only get around 11,200 or so in 3dmark05.
If you guys have any ideas I would appreciate them.
Thanks,
Marlon
Sorry for repeating the question, but to increase the delta, do I have to use pencil on the condusting place on the left side from resistor K?
If you are talking about the geometric delta clock, then no, you can't shade a resistor to change that. It has to be changed in the bios of the card.Quote:
Originally Posted by Ening
If your talking about another delta, then I'm not sure what you are talking about.
Marlon
I definatly think your card is bottlenecked by the CPU. My first card scores 6750 in 3dmark06 at 724/921.Quote:
Originally Posted by C-BuZz
http://service.futuremark.com/compare?3dm06=229525
I only have a higher score than you because my CPU score is so much higher. Your FPS and SM 2.0 and 3.0 score are better than mine. With a better CPU your scores would ROCKET!!
Marlon
Whoops. Sorry. I meant this mod for switching frequency:Quote:
Originally Posted by snakeskinner
I don't know why I wrote "geometrical delta". But what about switching frequency, is that place to the left?Quote:
And than comes a very important Mod, being resistor K.
This resistor measures ca 80Kohm, and sets the switching frequency.
Connecting a 100Kohm resistor in parallel, almost doubles the switching frequency, and solved my problems completely.
You could eventually do this mod by pencil, try to get the value down to approx. 45Kohm.
Sorry for noob question.
um that's entirely clear in the post.
measure the resister in question and adjust your probe orientation till you see 80kohm as the default value.
then pencil over the top of the resistor till the provbes, using the same orientation, reads 45kohm.
pencil dust is not very reliable a conducter so try blow any loose carbon far away from any part of your card and default to a higher value.
i find that resistence can move based or things like humidity or temperature so to be safe rather aim for 55kohm with the pencil.
if you go to low like 30kohm first blow as much off as possible and then touch the pencil mark with say your finger to remove some dust.
you should quickly see just how dicy and unstable pencil modding really is.
i don't think it's a viable long term solution.
for a quick bench ok fine but be carefull and don't expect the value to remain where you set it initially.
it would be wise to check a pencilled resister every day before starting a rig or measuring the resultant outpu regularly so voltage output creep can be noticed before it becomes deadly.
I read this thread a few times over and decided to go for it myself. I ended up doing this. I thought I was going to get 1.4Vgpu, but ended up with 1.5Vgpu, not to mention the core will run up to 725mhz from 570 on stock volts. Any ideas?
Edit: Idles @ 44C / Load @ 62C. Zalman VF-900. Ambient of 24-26C.
What do you need ideas about? That is the mod for 1.5v. If you only wanted 1.4v you should only have grounded D511. If your max load is 62 then you're fine, but I wouldn't go much further without better cooling. Have you done any real stess testing to verify that 725 is stable? Mainly: have you run ATItool (version 0.24 beta 14 which works with nVidia cards) and run the artifact scanner to verify you're not overclocking too high? Run the scanner for a good 25min and if you get no artifacts you're good to go. Atleast, that's how long I run it for to be sure because I've had zero artifacts for 10min only to have em show up a min later like crazy.
Some good (i suppose) & bad news.
Bad news, card is dead.. for now :)
Good news is dont use 1.85v on the core :slapass: Now ya know.
The chip circled bottom left (attatched pic) caught fire... literally, & went up in smoke when I turned pc on. I need some info on what type of chip it is. I cant tell what type of chip it is as it's all charred & burnt. If someone could take a close up & provide some information on it be much appreciated :)
Chip has been removed & i'll try source a replacement to see if I bring her back from the dead..
Thanks
C-BuZz
I just want a solder mod :(Quote:
Originally Posted by Nosfer@tu
I dont give a rats ass about my RMA posebilityes. Just want a good old fasion Variabol resistor on GPU and VMEM, :( Help???
Look one post above yoursQuote:
Originally Posted by Nosfer@tu
Imossible unless you only want max 0.05-0.07v increase, if so see the first two pages of this threadQuote:
Originally Posted by Nosfer@tu
That chip is not for the vgpu at all, it is for vmem. I think it would be impossible for that chip to burn up by doing the vgpu mod though I've been wrong one time before in my life :PQuote:
Originally Posted by C-BuZz
Can you describe the mod you did in more detail/pictures?
See this thread for info, I'm sorry it will not get your hopes up very much though...
http://www.xtremesystems.org/forums/...ad.php?t=96983
what were you running your memory voltage at please.Quote:
Originally Posted by C-BuZz
we need to figure out what vmem is safe for 24/7.
The numbers on the chip areQuote:
Originally Posted by C-BuZz
4420
BA6C13
The burned component is a N Mosfet.Quote:
Originally Posted by C-BuZz
It is used by the Vmem switching regulator as one of the two switches.
One is connected to ground and the other to V+.
The one that is burned on your board is connected to V+.
To burn out such a Mosfet means that both Mosfets are conducting at the same time, which in turn means that the voltage regulator was not functioning properly.
May be you have increased Vmem by lowering the value of a resistor, and maybe a short cicuit occured.
Anyhow, you will have to replace both Mosfet's, remove the extra resistor that increased Vmem and hope that everything is still working.
What you need are two N Mosfets with a channel resistance of 10mOhm or less, a max current of 100 Amp and a continous power of several watt.
The housing is a SO-8, but other housings can be used also.
An example is the IRF7821.
sorry - quoted this again.. but)Quote:
Originally Posted by C-BuZz
DOH! that suuuuuuuuucks. sorry to hear about this. that's one of the chips that poeple sink because of over-heating issues with these vmods. That one and the one to the right and up just a tad..
Thx for answering me. I have 2 7900 GT awaiting modding and a few more comming in next week.Quote:
Originally Posted by Per Hansson
I just though that when "Resistor "J" was replaced with 50 K0hm non variabel resistor" the Shamino mod would be posible aswell??????
But gees not.
BUT IT SUX!!! So when benching you have to remove your card and redo the conductive ink :( :banana::banana::banana::banana: :(
Thx all for your input.Quote:
Originally Posted by t024484
I did not touch Vmem @ all & I had no vmem mods other than pencil mod in place. Only thing I increased was the Vcore. Please point out the second mosfet that needs replacing.
The mofset has a small metal pad underneath it, whith 6 contact points (contact points where underneath the metal pad connected to the pcb) the metal pad came off with the chip. Which was connected the the unburnt pins. What purpose do they serve?
In the first pic the contact point on the first pin seems to have completely burnt out? Anything I can do about that? Or just pray it still makes contact?
I did not notice any other burnt out chips, only the 1.
Thanks again :)
C-BuZz
Cant find the IRLR7821 N Mofset anywhere local :(
I have 2 big electronics stores close buy but not to sure which Mofset I could use as a replacement.
http://www.jaycar.com.au/ or
http://www.dse.com.au/
Can someone please point out a suitable replacement Mosfet. I can handle soldering one like this on no probs :)
http://www.xtremesystems.org/forums/...9&postcount=38
Thanks
C-BuZz
you don't have to use conductive ink, and you don't have to redo your mod everytime you want new voltage. you can use switches between the mod points and ground to toggle the +.05v, +.1v, and +.2v aswell as a switch to toggle between the 5k resistor and 50k resistor to toggle the base voltage between 1.2v and 1.5v. Doing so lets you adjust from 1.2v to 1.85v in .05v increments (though going higher than 1.7v is risky with any cooler and you'd need to adjust overcurrent protection to go over 1.7v)Quote:
Originally Posted by Nosfer@tu
Here's how you'd use a switch to toggle 5k and 50k:
http://www.xtremesystems.org/forums/...1&d=1146359748
Here's a breakdown of the different groundable points if you want to use a dip
switch.http://www.xtremesystems.org/forums/...1&d=1146356347
One thing is for absolute sure!
Do NOT overclock these card without adding a stick-on heatsink to those 2 chips that get boiling hot. So hot that is clear the they melted the solder off one members card and the chip fell off! Crazy.
Im using a copper stick-on heatsink and still it gets hot but not hot enough to damage anything.
Anyway, I did the 100k mod with the 1.7v core mod and it screwed everthing up. The card flashed video on and off and on and off. :(
I pulled the 100k resistor off and reverted back to 1.5v core and now the card does not overclock as high as it used to. :(
100K resistor? It's supposed to be a 50K. Was it two 100K in parrallel or a 100K variable or did you simply use one 100k resistor? Also, did you try 1.55, 1.6, etc first or did you jump straight to 1.7? what kind of cooling are you using?
@onion, what are the two chips that get extremely hot? Could you post a pic please?
Also, did you do the 1.7v mod AND the 100k mod at the same time? I bet if you did that it was the 1.7v through the core that did more damage than the 100k mod. If not, then I think its important to figure out if you did anything wrong or if the mod isnt needed on some cards.
Here is my setup.
At first I did the 1.5v mod by changing the resistor to 50k. I used two 100k in parallel to equal 50k. I also used the massive VF1 cooler with fan Picture so temps were very low. Everything was GREAT. I was running over 650mhz core rock stable and the core was at a cool 52c at full load. I was very happy with the results.
But I wanted MORE. I installed the 100k resistor in parrallel with the 80k "k" resistor as mentioned in this thread to boost freqency to the voltage regulator. Then I did the 1.7v mod. It was a BAD move! everything was Very unstable. I first ran 700mhz and the screen started to flash on and off and on and off. I dropped down to 650mhz and the same thing happen. Finally stock speeds were fine and stable. I removed the 100k and 1.7v and now the card does not even run stable at 650mhz and Im even getting tons artifacts at 600mhz. Stock speeds everything is fine though. So now Im back at 1.5v and the card does not clock even 600mhz :(. Below is what I did when the problems began. :( Note that the 100k resistor leads are NOT touching any part of the PCB even though it looks like it is in the pic below.
http://www.fatonion.net/7900final2.jpg
These are the two chips that get BOILING HOT and MUST be cooled!! As you can see 2 members have already fried thier chips! Just put on a stick-on heat sink and you'll be fine. My heatsinks get really warm but thats good. Far from hot enough to damage anything though so as long as you sink them chips you will be 100% fine. Sorry for the blurry pic. Just sink them 2 chips!!!!! The smaller one gets much hotter than the larger by the way.
http://www.fatonion.net/7900hot.jpg
ah, that 100k resistor mod. jumping straight to 1.7v was a bold move onion. Good thing you had those sinks on the back of the card. Otherwise your card might be totally dead. Word of advice: if you change anything in a computer system only change one thing at a time. That way if you have problems you know exactly what caused them. Also, when overclocking anything and you need more voltage, only increase the voltage in small increments as needed so you can monitor performance, temps, and artifacting.
I'm running 1.5v right now but did the pencil mod for the switching frequency and wound up getting higher stable clocks after said pencil mod. I'd say it was the 1.7v that caused your problems. Sry you lost you clocks. Hopefully after the card has settled down for a while you'll be able to push it back to 650 again.
Quote:
Originally Posted by snakeskinner
Anyone have any ideas on this yet?
Marlon
Marlon, you sure your meter is working correctly? Are your leads good and sharp? Are you using a good ground with the black lead when measuring mem voltage? 830 is a pretty good o/c for the memory without any volt modding. Esp if it is, in fact, only getting .8v; which doesn't sound like the case given you got 830.
Also, who made your card? Double check that you are using the correct measuring point for the vmem:
After a fair bit of searching I found this locally:
http://www.jaycar.com.au/products_uploaded/BUZ71.pdf
14A, 50V, 0.100 Ohm, N-Channel Power
MOSFET
This is an N-Channel enhancement mode silicon gate power
field effect transistor designed for applications such as
switching regulators, switching converters, motor drivers,
relay drivers, and drivers for high power bipolar switching
transistors requiring high speed and low gate drive power.
This type can be operated directly from integrated circuits.
Formerly developmental type TA9770.
Features
• 14A, 50V
• rDS(ON) = 0.100W
• SOA is Power Dissipation Limited
• Nanosecond Switching Speeds
• Linear Transfer Characteristics
• High Input Impedance
• Majority Carrier Device
• Related Literature
- TB334 “Guidelines for Soldering Surface Mount
Will this work as a replacement? Sorry not sure on how to read the electrial characteristics :(
Thanks
C-BuZz
Hey if it does, and if it runs significantly cooler than the stock one, I may voluntarily replace that chip! :toast:
It seems to run at a rediculous temperature even after removing all mods. :nono: nvidia. That little chip is the single hottest in my PC.
ouch sorry to hear mate, hope you can fix it :)Quote:
Originally Posted by C-BuZz
The Mosfet that you found is not good enough. It should have a channel resistance of less than 10mOhm. This one has 100mOhm, meaning that the power dissipation will be 10 times higher ( I*I*R).Quote:
Originally Posted by C-BuZz
Also the current is too low with 14A. Max Current should be between 50 and 100Amp.
The IRF7821 can be bought from: www.farnell.com.
I also found a supplier for the original SI4420: www.elfa.se.
Both Mosfet types are made by International Rectifier.
Both Mosfets on your board should be replaced. You can use the same Mosfet.
Good Luck
to24484, what is your opinion on that chip running so hot?Quote:
Originally Posted by t024484
Is it likely that a replacement (non-identical but adequate) could run cooler?
Do not worry about the pin that is burnt away.Quote:
Originally Posted by C-BuZz
It is one of the three "Source" pins from the Mosfet.
You still can connect the other two pins to the board, that will do.
The Pin most to the right is the "Gate" and the four pins to the other side are the "Drain" of the Mosfet.
The second Mosfet to be replaced is directly under the damaged one, and is called "4410". This one is a Mosfet with slightly less specs than the 4420, better to use the same Mosfet for both.
The point that you probably refer to as "contact points" are just solder points in case of using a different type of mosfet with a solid underplate "Drain" instead of the four discrete pins, like the ones used for the Vgpu regulation (Q506 and Q510).
So take no notice of these "points", you won't need them.
The reason the Mosfet gets so hot is because of a) its Channel resistance R and b) because of the switching on and off that takes some time.Quote:
Originally Posted by xit
The heat generated when switched on is I*I*R, with I being the current that is flowing.
The heat generated in the switching on and of, depends on several aspects like the Mosfet's caracteristics and the Voltage regulator.
There are two ways to reduce the heat, the easiest one being the use of heatsinks.
The other one is to use Mosfets with a lower Channel resistance and/or a faster switching characteristics, which is not too easy to achieve since the Voltage regulator is also involved.
The fact that the Voltage regulator is also getting hot, can only mean that the switching process is done with significant losses, but you will either have to find better Mosfets (IRF7821 ?) or use another heatsink.
Ok i've got a couple of these IRLR7821 N Mofsets underway for some testing. Will update when they arrive..
Farnell do not have IRF7821 listed on there AU catalogue.
http://au.farnell.com/jsp/home/homepage.jsp
I'll do some basic testing with these until I can source IRF7821.
Thanks for your help, much appreciated.
C-BuZz
Thanks, that is very informative indeed.Quote:
Originally Posted by t024484
Do you think that nVidia should have specced a better part that wouldn't get so hot even at default volts? It seems odd to me that these 2 tiny parts would end up being the hottest components in my PC. Perhaps nVidia should have specified them as parts requiring a small thin heatsink if a better (cooler) component was simply too expensive in comparison?
I gather it was essentially heat and not volts that caused Cbuzz's to explode, and therefore a heat sink at say 1.7 volts would make overvolting virtually 'safe'?
My other question is about why the GPU volt mod seems to increase RAM overclocking without doing a RAM mod specifically. I read previous that this 'hot' component in question was based around RAM and not GPU?
i have read the whole thread, but i didn't found something about this mod on a 7900 GTX, because i think i have the same problem like t024484, that ati tool works on high frequencies, but at comanche or 3dmark 2005 i get a blackscreen.
http://www.xtremesystems.org/forums/...6&d=1143538288
"And than comes a very important Mod, being resistor K.
This resistor measures ca 80Kohm, and sets the switching frequency.
Connecting a 100Kohm resistor in parallel, almost doubles the switching frequency, and solved my problems completely.
You could eventually do this mod by pencil, try to get the value down to approx. 45Kohm."
on my 7900 GTX the U502 is near the pcie connector.
It may be that is has to do with the memory chips. I have no idea what the spread in current demand is, or is it the voltage regulator chip that is making the difference? The two Mosfets are supposed to switch in alternation. If one mosfet is turned on while the other is still conducting for a short period, this causes a short circuit with huge currents to flow from 12V to ground.Quote:
Originally Posted by xit
Funny enough, the two components on my board do not get hotter than 50C.
The 1.7 Volt is for the GPU. The Mosfet that burned out is for Vmem.Quote:
I gather it was essentially heat and not volts that caused Cbuzz's to explode, and therefore a heat sink at say 1.7 volts would make overvolting virtually 'safe'?
Speed of information coming and going from RAM to GPU depends on speeds on both sides. If one of both gets faster ( set up time, hold time, etc )by applying more voltage, the frequency between the two can be increased.Quote:
My other question is about why the GPU volt mod seems to increase RAM overclocking without doing a RAM mod specifically.
thz alot mate. made me a lot more confident :)Quote:
Originally Posted by quijonsith
When you have chips that you know will get hot, you can manufacture them with the die mounted directly onto a metal pad, then encase the die, pad, etc in epoxy as usual. In the finished part, the bottom of the metal pad is exposed to the outside, on the bottom of the part. Now you can solder that metal pad to the board, and this allows heat out of the die more quickly than if the part had no exposed pad. In essence, you're using the PCB as a heat sink. It's not a great heat sink, but it definitely helps.Quote:
Originally Posted by C-BuZz
If you've burnt a pad on the board then you're at a bit of a disadvantage, to say the least. The sort of currents that were being switched on this part apparently required multiple leads to guarantee low R, and losing one pad means the other three now have to pick up the slack. If you're ambitious, you could hard-wire the pin to it's source, bypassing the traces on the board.
I wouldn't count on the integrity of a burnt pad - even if you can solder to it, there's no guarantee that the trace supplying it is in good shape.
Edit: Looking at the datasheet, I see you've lost one of the three source pins. I don't know if the part has those three pins each bonded to the die or they are joined in the leadframe and then bonded as one. If it's the former then I'd say there's a problem. If it's the latter then maybe not.
Thanks for your input.
The metal pad is still intact & in good shape. The pad was sitting on top of the 6 contact points which would mean that they are all connected somehow & transmitting current (if there's a current flowing through it). The chip was sitting on top of the metal pad like a sandwitch.
The metal pad (very thin metal sheet) WAS actually connected to the 4 x unburnt pins & sitting under the chip. However when I removed the chip the pad snapped off with the chip. Which would also mean that the 4 x unburnt pins & the 6 x contact points were all connected to each other somehow :confused:
Cheers
C-BuZz
Ok, i'm an idiot, I either looked at the wrong picture or read it wrong, cause I was measuring the wrong place for the memory voltage. I just checked again and its at 2.00.Quote:
Originally Posted by quijonsith
Still nothing on the resistor marked "K" in the first post. I double checked it, and I'm on the right resistor for sure. My meter is working fine because it was reading the resistor for the mem voltage right. One side of that resistor is ground, and I get a good reading on that side. The other side I can't get anything.
I don't know much about how this stuff works, or what it does. But will the card even run if that resistor isn't working? And if it will, what will it do? I been playing oblivion on the card with no problems. Maybe there is just some hard coating on one solder pad that won't let me get a good connection to it, but I scraped it off pretty well.
BTW, card it EVGA, stock clocks 450/660.
Thanks,
Marlon
make sure your lead is decently sharp and, in the words of my shop chief, "stab the f**cker". sometimes you gotta stab into the solder pretty hard to get the reading.
Yes so I thought, but Cbuzz says that he only overvolted the GPU and his MEM was at default volts. Why would that cause this mosfet to burn? Could it be burnt running MEM at 800 or 900 MHz even at default volts?Quote:
Originally Posted by t024484
I'm amazed that your mosfets are only at 50 degrees....have you heatsinked them? What GPU / MEM volts have you settled on?
I am looking to get a few of these to do the job of cooling the mosfets. They come in either copper or aluminium, but I imagine that copper is better?
http://www.scorptec.com.au/index.php?prdid=10331
On that part the metal pad on the bottom of the chip is connected to the drain. The drain is also connected to all four leads on the side of the chip that didn't burn, so yes, you actually have (had) a lot of contact area for the drain.Quote:
Originally Posted by C-BuZz
The contact pad coming off the board is not great, but even if it had stayed on the board you wouldn't have been able to solder the replacement part to it anyway. With the loss of the pad and the source lead, this board's clockability may suffer.
I should be able to fabricate somthing so the points are all contacting the drain area. Anyway, replacement chips due in tomorrow so i'll see how it goes :) **fingers crossed**Quote:
Originally Posted by sluggo
Thx for your help, I understand how it all works now :toast:
C-BuZz
actually I said the only mem mod I had in place was the pencil mod. The mem was highly overclocked @ 505mhz ;)Quote:
Originally Posted by xit
C-BuZz
Oops, i missed that. Thought you only had GPU mod.Quote:
Originally Posted by C-BuZz
So is the opinion that GPU volt increase alone won't cause those mosfets to heat up much above normal? They do seem to run hot !
Well I managed to burn out a MOFSET also. Not one of the ones that gets too hot either. I dont know what happened. I've attached a pic of the one I burnt. It burnt only in the middle,so I can read the letters on top: "119n03s". Could someone please tell me if there is any more writing on the MOSFET? Thanks.
Also, I found this link http://www.ortodoxism.ro/datasheets/...3S_Rev1.11.pdf
It looks and sounds like the one I need. NOw does anybody know where I can buy maybe just 10 of these? I found batches of 5000. Group buy anybody? lol
Somebody with some info help me. :D
NOTE: Sorry, I borrowed the pic, hopefully no one minds.
As I mentioned earlier, there are two types of Mosfets in this SO-8 shape, either with 4 drain pins, which is the one that is burnt on your board, or with a solid drain plate under the housing, like Q506 and Q510.Quote:
Originally Posted by C-BuZz
Because your mosfet exploded, you have a distorted view of the original situation.
Inside the Mosfet is a metal carrier to connect the drain to the outside pins, this carrier is normally unvisible.
Because of the desintegration, you got the impression that this plate was connected to the metal surface on your board, which was not the case, only the 4 pins where connected. Look at the 4410 next to it and you see what I mean.
Mind that overclocking the memory and increasing the Voltage like you did, increases the current with at least 70%. So using a heatsink in those cases is mandatory.
You do not have to construct anything. The Mosfet you have ordered has a different shape with only one source pin, one gate pin and a backplate for the drain. Instead of having the gate right and the source left, this fet has its gate to the left side and the source to the right, so be aware of that.
The first step of your investigation should be to find out if your board is still functioning, don't worry too much about things that are only second priority.
Take the IRF7821 from www.farnell.com They are cheap and upwards compatible, and can be purchased in small quantities.Quote:
Originally Posted by John600rr
Ahhh I see. That explains that then. When I removed the burnt Mosfet it basically crumbled into small pieces as it was totally fried like a piece of charcoal. The metal plate was actually within the Mosfet. I thought it was actually underneath the mofset..Quote:
Originally Posted by t024484
I am aware of the different orientation of the replacement mosfet, I have read your guide how to install it correctly in another thread.
I searched the entire farnell Australia website for a SO-8 version of this particular mosfet but I could not find it in there catalogue :( I hope this replacement will be ok for some basic testing of the board.
I will test the board tomorrow & see if it is still functioning.
Thanks
C-BuZz
What mods had you done (GPU and RAM?) and to what voltages?Quote:
Originally Posted by John600rr
I'm trying to get an idea of what is 'safe', so to speak.
Can anyone please tell me which Mosfets I have to cool when I do the 1.4-1.5V mod at GPU? Pics would be nice! :)
Thanks..
Are you sure it will work? I've compared the two data sheets and they seem simular (albiet I don't know 2% enough to understand anything).Quote:
Originally Posted by t024484
What I need:
http://www.ortodoxism.ro/datasheets/...3S_Rev1.11.pdf
What you advised:
http://www.irf.com/product-info/data...irf7821pbf.pdf
You seem to know what you're talking about so if you're sure, I'll go with it.
Thanks for your help. Someone mentioned a thread about soldering MOSFETs, could somebody link me to it, I'll be needing it. Thanks.
Sorry for being off-topic.
Quote:
Originally Posted by xit
I was running 1.5V on the GPU and 2.2V on the ram.
GPU was the double trace mod (I posted about page ago) and the memory was done via pencil. (570ohms)
I ran 725mhz/1908mhz through the card at about 64C MAX load temp.
I dont blame the OC on the burnt MOFSET, I believe one of the wires measuring VGPU or VMEM came loose and shorted the card out. I wasn't there when it happened so I cant be sure. Dont let me result scare anybody.
Just do the Fingertest.Quote:
Originally Posted by Vega
Hold your finger firmly a few seconds on every component that is suspect, if it seems to be below 50C don't worry, if hotter you could use a heatsink.
Hehehe thats how I originally found the two hot spotsQuote:
Originally Posted by t024484
The Fingertest™ is great for troubleshooting hardware and finding the right partner :fact: :eek: :D
Alphaone, the BSC032N03 is a great component from Infineon.Quote:
Originally Posted by alpha0ne
It has a solid backplate for better cooling, the max channel resistance with 3mOhm is 3 times lower as all the others, meaning 3 times less heat dissipation, and it can handle 70 Watt if cooled properly instead of the 2.5Watt of all the others.
This is the best one I have came across so far. The big question is, where can you get it ?
One thing is for sure, MSI had also trouble with heat development
and found this solution !
So if the MSI 7900GT has this better mosfet that doesn't overheat, should we be exchanging our other branded cards for MSI's? Or is heatsinking simply better? I may still be able to exchange lol.....Quote:
Originally Posted by t024484
I have no idea. Maybe the MSI board has been improved on all aspects, can also be that they have changed other details to inhibit too much overclockingQuote:
Originally Posted by xit
Somebody with this board has to tell us his experience.
Well my MSI NX7900GT was a beast (I have sold it now, buying the Gainward 7900GT 512MB card) though 0502 still got very hotQuote:
Originally Posted by t024484
Optimised freq @1.2V
http://i16.photobucket.com/albums/b2...misedFreq1.jpg
Optimised freq @ 1.4V
http://i16.photobucket.com/albums/b2...ptimalFreq.jpg
'05
http://i16.photobucket.com/albums/b2...05701-9212.jpg
'06
http://i16.photobucket.com/albums/b2...06701-9222.jpg
:D :D :D :D :D :D
Its a nice card, but my EVGA SC hits 590/900+ (havent pushed mem more) w/ stock volts so we at least know the MSI's dont clock better, but they dont clock worse either lol.
When you reduce Rds in a mosfet you typically increase the Qg, or total gate charge. That's the case here, as the Infineon part has 3x the Qg of the IR part, and a corresponding increase in the turn-off delay. Dumping the increased gate charge 250k times per second leads to dramatically increased switching losses. Idle temperatures for the Infineon part will be significantly higher. Given that MSI is using it, though, it's certainly okay at stock switching frequencies.Quote:
Originally Posted by t024484
If you increase the switching frequency of the FET, however, switching losses increase linearly. An Infineon part with the frequency mod described here will have switching losses around 6x the IR part at stock switching frequencies. If the IR part is fairly hot at idle, the Infineon part will be very hot when overclocked.
My point is that overclocking the Infineon part will not necessarily be easier or even possible.
You have totally missed the pointQuote:
Originally Posted by madgravity34
my MSI card ran at 650MHz @ 1.2V but who cares, it means nothing
With coolbits you find the max optimised frequncy at stock V, thats what I was/have shown
that's one amazing OC for stock volts
It was/is an amazing card, by far the best I have ever owned but sold now and waiting for the Gainward 7900GT 512MB version but it looks like the circuitry is totally different on the 512MB model so very unsure ATM :confused:Quote:
Originally Posted by quijonsith
Pics for the Gainward 7900GT 512Mb
Any ideas where to start ?
http://www.tigerdirect.com.au/images...eftsidepcb.jpg
Full card pics here > HI RES > http://www.tigerdirect.com.au/images...llcardback.jpg
Yup. Read at least a dozen books on electrical engineering, study each chip on the card via white papers. After that you should be fine. :DQuote:
Originally Posted by graham_h
not what I wanted to hear :(
thanks for finding that pic graham. i've been wondering what has happened to the new pcb. it looks like they ruined the nice digital vgpu mod.
anyway i should have a 512mb gt in about a week and we can start working on the new mods