The Simple & Concise 7900GT Voltmod Tutorial

[redbox]

why was this removed from sticky?

 

[inveterate]

Hi guys i finally got the volt mod done.. the core is at 650mhz. quite stable.. The problem is I used ATI-Tool to overclock the card, everything is working fine, But under ATI tool the numbers are set to 650mhz for the core and 460 for the memory. But Nvidia monitor says 920mhz. I know that with the nvidia menu u assume Double what the Bar says. So with the ATI tool do i Assume 4x what the bar says????

 

[compgeek89]

Yes, 4x

I got my cores stable @ 760mhz with the 45k ohm resistor mod along with the 1.55ink mod.

 

[Ike0069]

resticky!

 

[Xpage]

what are your temps compgeek89, also what gpu cooler are you using?
I don't think I have the balls to OC it as far as you did.


I'm going to sport a koolance GPU cooler, waiting for the 7900 to come in the mail. Going to have a fun week building my pc.

 

[compgeek89]

water

 

[dbunder]

Brilliant tutorial, fuzz! Can't wait to get my new mobo and processor so I can finally get to using my XFX 7900GT that's been gathering dust...

This is a simply HUGE post and I can't read it all, so this info is probably in the post somewhere already. What kind of cooling are all of you that're using the gpu and mem voltmods using? I'm planning on a VF900Cu and copper OCZ ramsinks. The XFX stock cooler looks fairly solid, but I wouldn't trust it to cool at these insane speeds.

Hope I don't break anything... wish me luck. :laugh:

Oh, does anyone know of any retail stores that carry the $3 multimeter? There's a Radio Shack up the road within walking distance, but $3 is better than $20 for something I'll likely only use once or twice. The closest Harbor to my house is around 70 miles. :roll:

 

[tiwas]

Quick question:
If I do not use the vmod, do I still need extra cooling for my ram? I'm using water, have a big fan in the rear, two smaller in front, and a big one coming down from my PSU.

Just want some more juice out of it, but not taking it to the max. The plan is a 1.4vmod and then maxing out what I can get from it.

 

[redbox]

Originally posted by: dbunder
Brilliant tutorial, fuzz! Can't wait to get my new mobo and processor so I can finally get to using my XFX 7900GT that's been gathering dust...

This is a simply HUGE post and I can't read it all, so this info is probably in the post somewhere already. What kind of cooling are all of you that're using the gpu and mem voltmods using? I'm planning on a VF900Cu and copper OCZ ramsinks. The XFX stock cooler looks fairly solid, but I wouldn't trust it to cool at these insane speeds.

Hope I don't break anything... wish me luck. :laugh:

Oh, does anyone know of any retail stores that carry the $3 multimeter? There's a Radio Shack up the road within walking distance, but $3 is better than $20 for something I'll likely only use once or twice. The closest Harbor to my house is around 70 miles. :roll:

I got my multimeter from walmart works pretty good.

 

[CKDragon]

Originally posted by: ueadian
http://www.xtremesystems.org/forums/showthread.php?t=94177 <<< the guy who originaly did this mod explains why people get Black Screens. He is way more technical then this one but its worth a read to find out how to fix the black screens.

Oh crap. I have to change a resistor?

Here's my story:
-Bought an EVGA 7900GT KO, Conductive Ink Pen from Radio Shack, & a VF900Cu
-The card ran fine before the mod, I used coolbits and did the "Find Optimal" to find the highest clock speeds, it worked as it should.
-Attempting the 1.5v core mod ONLY (no memory mod), I drew the lines using scotch tape & they appeared to be clean.
-Upon booting up, coolbit's "Find Optimal" sends it to the black screen loops. Sometimes 3D content boots up fine (at an improved 650 clock, so I know I'm working with a higher voltage) and I can play Oblivion seemingly forever, dependant on it getting past the initial load screen. When Oblivion fails to load, I get the black screens and have to reboot.
-Unhappy with the obvious instability, I erased the lines and re-drew the 1.4v line ONLY.
-Upon bootup, I get the exact same behavior except now I can only max out the core around 630.

So, from what I gather in this thread, I won't be able to volt mod until I replace a resistor? Gosh darnit...

Any help is GREATLY appreciated,
CK

 

[dman918]

ckdragon: lower your core. my 7900gt only gets 575 at 1.4v with a vf700...

 

[CKDragon]

Originally posted by: dman918
ckdragon: lower your core. my 7900gt only gets 575 at 1.4v with a vf700...

I will try to see if that increases stability with all the other programs, but does it make sense that I get the black screens upon hitting the "Find Optimal" within coolbits? Shouldn't it just go to the point where it's stable and then stop?

Thanks,
CK

 

[imported_crypt33]

the "find optimal" test is notorious for "killing" cards, or at least beginning the inevitable slide towards a defective card....mine ran fine at stock for a bit, as soon as i did detect optimal i got the blinking screen & had to downclock the memory to get the card to run all games...waiting for my new RMA'd card, supposedly from the new "good" Infineon-ram batch...hope the problem is solved

 

[dman918]

Just a FYI: I RMA'd my last card as it started having some weird artifacting issues. Got a new one with the infineon memory and scored a 10658 in 3dmark05 and 6056 in 3dmark06. Pretty good, though I was hoping to break 11000 in 3dmark05...

Oh, and my radioshack is selling conductive pens at half off, so it was only $6.50. You may want to check yours to see if they are on clearance there too.

 

[munisgtm]

what voltage and max limit for both mods you guys would suggest for a 7900GT with stock cooler and no ram sinks and stuff

 

[happy medium]

bump

 

[munisgtm]

no reply?

 

[happy medium]

bump I want to see more results and benchmarks?

 

[Ike0069]

Does this work the same on the 7950GT?

 

[dbunder]

Going to install my Zalman vf900-cu tomorrow and some ramsinks (passive, but the Zalman blows across them nicely) and try the GPU voltmod to 1.4v. 1.5+ seems a bit overkill to me. Is it safe to do the GPU mod without doing the RAM mod concurrently? I'm kinda weary about the rAM mod.

Wish me luck, and any input is appreciated!

Luckily, with my cruddy XFX stock cooler, I idle my GPU at around 42C and load it around 55C, so I shouldn't have any issues!

edit: what's a good stress test to see if the card is stable after either mod (or both)? atitool has never worked well for me. it just completely bombs after a while no matter what. 3dmark 06 maybe? that always seems to bomb if i overclcok my stock card, but if it loops 10x through all tests (esp. the hdr ones), i know i'm golden. good idea? or is there something more i can use?

 

[fuzzybabybunny]

Originally posted by: dbunder
Going to install my Zalman vf900-cu tomorrow and some ramsinks (passive, but the Zalman blows across them nicely) and try the GPU voltmod to 1.4v. 1.5+ seems a bit overkill to me. Is it safe to do the GPU mod without doing the RAM mod concurrently? I'm kinda weary about the rAM mod.

Wish me luck, and any input is appreciated!

Luckily, with my cruddy XFX stock cooler, I idle my GPU at around 42C and load it around 55C, so I shouldn't have any issues!

edit: what's a good stress test to see if the card is stable after either mod (or both)? atitool has never worked well for me. it just completely bombs after a while no matter what. 3dmark 06 maybe? that always seems to bomb if i overclcok my stock card, but if it loops 10x through all tests (esp. the hdr ones), i know i'm golden. good idea? or is there something more i can use?

Both the RAM and GPU mods can be done seperately and safely. A good stress test is 3Dmark, like you said. If there are artifacts, tone down the overclock until you don't have any more artifacts.

 

[dbunder]

Thanks!! I'm dumb and forgot to ask something though. What's a decent program to overclock, since coolbits won't go that high? Like I said, ATITool is wonky for me. Never been much into GPU overclocking (since i've never been able to get a decent OC), so I don't know about all the tools.

 

[fuzzybabybunny]

Originally posted by: dbunder
Thanks!! I'm dumb and forgot to ask something though. What's a decent program to overclock, since coolbits won't go that high? Like I said, ATITool is wonky for me. Never been much into GPU overclocking (since i've never been able to get a decent OC), so I don't know about all the tools.

Rivatuner does a good job.

http://www.pcstats.com/articleview.cfm?articleid=1803&page=5

 

[popstop]

I picked up a Gainward Bliss 7800GS+ recently (which is basically like a 7900GT but slightly slower core & mem clocks) and managed to hit 650mhz on the core with the standard 1.2v. I havent experienced any major artifacts... the only place where some weirdness happens is in 3dmark05 with the blimp/dragon test. Is it safe to keep the core this high on stock volts? Coolbits test fails at 660. Memory is fine up til 730.

Edit: temps at this overclock at load is 70 degrees. Is that hot for G71 cards?

 

[CKXP]

Originally posted by: popstop
I picked up a Gainward Bliss 7800GS+ recently (which is basically like a 7900GT but slightly slower core & mem clocks) and managed to hit 650mhz on the core with the standard 1.2v. I havent experienced any major artifacts... the only place where some weirdness happens is in 3dmark05 with the blimp/dragon test. Is it safe to keep the core this high on stock volts? Coolbits test fails at 660. Memory is fine up til 730.

Edit: temps at this overclock at load is 70 degrees. Is that hot for G71 cards?

what kind of wierdness did you notice(artifacts/anomalies)? also your temps are fine, what program are you using to monitor them?

that's impressive that you got the core that high with only 1.2v, but you might be pushing it in terms of stability. i can get 650mhz on my 7900gt, but that's with a 1.4v mod, and it's not 100% stable.