Official 7900GT Volt Mod Thread.

VinnyTAMU · May 8, 2006

g0dM@n said:
Really? Could you link to where it states that the bios flash fixes it? I'm sure some people might very well be happy with this info!

Yes please. I have an EVGA 7900GT and I would like to has this information if any problems arise. I will be doing this volt mod, but not untill I have put this card thru its paces and deterimed it has no defects.

soloz2 · May 8, 2006

g0dM@n said:
Really? Could you link to where it states that the bios flash fixes it? I'm sure some people might very well be happy with this info!

I can't remember where I saw it... there was a thread either at dfi-street or overclock.net

if I come across it again I'll try to remember to post here

VinnyTAMU · May 8, 2006

Well just did about 40min of research on this (instead of much needed studying) and found this http://forums.guru3d.com/showthread.php?t=179691. The information about bios updates starts around page 5/6. However after reading most of the posts it looks like the bios updates helps some but not everyone. Alot of people seem to also think that the Hot voltage IC's on the back of the card need to be sinked and may be causing problems.

Also a user on this form also posted this link, which he says applies to the some 7900GT's as well.

But still not 100% conclusive as to a fix.

Alien1099 · May 8, 2006

I volt modded my eVGA 7900GT yesterday by 0.3 volts and it allowed me to push the core to 690MHz and the RAM to 875 (1750) using coolbits. At 696 and 881 coolbits registered it as unstable. The stock settings are 550 and 780 (1560) I do believe, so it was quite a jump in performance! I'm using a Zalman vf900cu to keep it cool. While playing Oblivion with most of the detail settings maxed, it never seemed to get above 50° according to the Nvidia Control panel.

Before the volt mod I was only able to push the core to 565, but I had the RAM at 900. Now it doesn't wanna go past 881 for some reason. Oh well, I will gladly sacrifice 40MHz in memory speed for 125 more MHz in core speed.

I used the conductive pen which was sort of a pain because it kept spitting out too much liquid.
http://members.cox.net/alien1099/case03.jpg

snakeskinner · May 8, 2006

Alien1099 said:
I volt modded my eVGA 7900GT yesterday by 0.3 volts and it allowed me to push the core to 690MHz and the RAM to 875 (1750) using coolbits. At 696 and 881 coolbits registered it as unstable. The stock settings are 550 and 780 (1560) I do believe, so it was quite a jump in performance! I'm using a Zalman vf900cu to keep it cool. While playing Oblivion with most of the detail settings maxed, it never seemed to get above 50° according to the Nvidia Control panel.

Before the volt mod I was only able to push the core to 565, but I had the RAM at 900. Now it doesn't wanna go past 881 for some reason. Oh well, I will gladly sacrifice 40MHz in memory speed for 125 more MHz in core speed.

I used the conductive pen which was sort of a pain because it kept spitting out too much liquid.
http://members.cox.net/alien1099/case03.jpg

If your memory would go higher before the mod than after the mod, it sounds as though you could have a power supply problem. Could be either the PSU of the regulator on the card itself. For some reason you are not getting enough power to push the core AND the memory that high. Try lowering your core about 20 or so and see if the memory can go back up to 900. If it can, its probably a power problem.

You could also try the switching frequency mod. For some it helps while others it seems to do nothing. In your case I suspect it might help get your core and memory high and stable together.

Marlon

crimedog · May 8, 2006

i too got slightly lower mem clocks after modding. i have done the 1.5v hard mod and the swiching frequency mod, and i have plenty of power. also have those IC's sinked. some cards are just different. i also suffer from flashing screen every once in a while, can't seem to figure it out. apparently some cards just do this.

soloz2 · May 8, 2006

VinnyTAMU said:
Alot of people seem to also think that the Hot voltage IC's on the back of the card need to be sinked and may be causing problems.

I have not experienced any problems with my 7900GT, but as soon as I got it I put my water block on it... well I threw itin my rig for 5 min just to make sure it wasn't DOA I did the 1.4v mod the same day I got the card and I did the 1.5v mod the next day. My card runs stable 685/1700 on 1.5v I'm thinking about doing the 1.55v mod to see if I can reach 700/1700

I did put a BGA RAMsink on the back of the card where people were indicating the IC's getting hot. I managed to use one RAMsink to cover both of them. Here's a couple pics of where I placed all my RAMsinks.

the front of the card is the basic setup

the larger RAMsinks are Swiftech ones, and the two small ones I believe to be OCZ ones, but I'm not sure as they came with my gpu block (bought it used)

and the back of the card

again, this is one of the smaller RAMsinks that came with the gpu block I bought used. I believe it to be an OCZ copper RAMsink, but as I don't have any RAMsinks I know to be OCZ I cannot compare.

I hope this helps

{PMS}fishy · May 8, 2006

soloz2 said:
I have not experienced any problems with my 7900GT, but as soon as I got it I put my water block on it... well I threw itin my rig for 5 min just to make sure it wasn't DOA I did the 1.4v mod the same day I got the card and I did the 1.5v mod the next day. My card runs stable 585/1700 on 1.5v I'm thinking about doing the 1.55v mod to see if I can reach 600/1700

I did put a BGA RAMsink on the back of the card where people were indicating the IC's getting hot. I managed to use one RAMsink to cover both of them. Here's a couple pics of where I placed all my RAMsinks.

the front of the card is the basic setup

the larger RAMsinks are Swiftech ones, and the two small ones I believe to be OCZ ones, but I'm not sure as they came with my gpu block (bought it used)

and the back of the card

again, this is one of the smaller RAMsinks that came with the gpu block I bought used. I believe it to be an OCZ copper RAMsink, but as I don't have any RAMsinks I know to be OCZ I cannot compare.

I hope this helps

Something is not right. It should not take 1.5v to hit 600 core. Unless you got a really bad card. I was able to run 585 core on stock volts, and 620 with stock cooling and 1.3v.

What are the tempatures that you card is reporting under load?

soloz2 · May 8, 2006

load temps of 38-40 is what it reports... but then again it reports the same for idle, which seems a bit wierd, but I figured it had to do w/ giving it 1.5v all the time

g0dM@n · May 8, 2006

{PMS}fishy said:
Something is not right. It should not take 1.5v to hit 600 core. Unless you got a really bad card. I was able to run 585 core on stock volts, and 620 with stock cooling and 1.3v.

What are the tempatures that you card is reporting under load?

could be his rails...

soloz2, do you have a dmm to check your rails with?

soloz2 · May 8, 2006

yeah, my rails are stable... well i've only tested 5v and 12v, but I assume my 3.3v rails are stable... not sure how to test them.

I've got a Seasonic S12-600 psu which is a pretty good psu.

and I tested the voltage on my card after the vmod and it's dead on what it should be

Qubix · May 8, 2006

I recently got a EVGA 7900GT that was clocked at 520/1540 out of the box. Overclocking went up to 540/1840 with stock volts, kinda disappointed in my gpu but very happy with my memory.

So I did the volt mod with dip switches to enable / disable memory volt mod and 0.1V / 0.2V and a variable 10k resistor on the memory. At 1.4V my GPU can do about 630 and my memory is up to an astonishing 1940 (970). Think both will do more and I am being limited by heat because my core actually went up to 665 with ATITool before detecting artifacts and clocking it back down to ~640. Variable resistor is at 12.5k actual resistance, haven't measured actual volts though. Have cranked it up to 2000 and got minor artifacting in ATITool and in games its hardly noticeable.

With my current setup of 630 / 1940 my 3D Mark '05 is 10728

p.s. I have noticed no pausing or screen flashes at all

soloz2 · May 8, 2006

{PMS}fishy said:
Something is not right. It should not take 1.5v to hit 600 core. Unless you got a really bad card. I was able to run 585 core on stock volts, and 620 with stock cooling and 1.3v.

What are the tempatures that you card is reporting under load?

lol... I just realized that I accidently typed in 585 instead of 685 lol

:bang head

with 1.4v I got 635Mhz and with 1.5v I got 685mhz max core. 1700 (actually 847Mhz so 1693Mhz effective)

I wanted to reach 700 core frequency... I'm not sure what I was thinking earlier.

my temps are still 40 load

g0dM@n · May 8, 2006

lol... HUGE DIFF between 585 and 685...

soloz2 · May 8, 2006

g0dM@n said:
lol... HUGE DIFF between 585 and 685...

yeah, I was just reading the new posts and saw reviewed what I said earler and was like...wtf... lol.. :bang head

Time4aMassiveOC · May 9, 2006

im probly gonna get the evga 7900GT KO is that one just as easy to mod?

soloz2 · May 9, 2006

Time4aMassiveOC said:
im probly gonna get the evga 7900GT KO is that one just as easy to mod?

all 7900GT's are exactly the same. The only differences are the clock speeds, some have a better cooler (eVGA Signiture and KO (I think) and the Asus TOP edition) and XFX has a few with black pcb and VIVO other than that they are all the same

VinnyTAMU · May 9, 2006

Yea I also get the random flashing when I change my memory. Also does everyones Auto Detect not work? When I try to auto detect nothing happens.

snakeskinner · May 9, 2006

VinnyTAMU said:
Yea I also get the random flashing when I change my memory. Also does everyones Auto Detect not work? When I try to auto detect nothing happens.

I have never used auto detect to detect anything myself. But after reading a few reports of people saying the auto detect was screwy, I tried mine and I can't get it to work. It just hangs up doesn't do anything until I cancel it. Its probably a driver issue with 84.21.

Marlon

KillrBuckeye · May 9, 2006

snakeskinner said:
I have never used auto detect to detect anything myself. But after reading a few reports of people saying the auto detect was screwy, I tried mine and I can't get it to work. It just hangs up doesn't do anything until I cancel it. Its probably a driver issue with 84.21.

Marlon

Are we talking about CoolBits auto detect feature? It worked on my card, and those are the settings I'm currently using. I recall that it did take about 5 minutes before the waitbar stopped scrolling and it returned the values.

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