7900GS overclocking.

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blade52x

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So I started overclocking my card and got some... results. On stock voltages (no mods or anything) the core begins to artifact above 570MHz - bummer because I was hoping for 600MHz but I guess I could reach that with a volt mod. The memory however, is just ridiculous. It doesn't artifact in ATI Tool until 924MHz! I ran 550/900 in ATI Tool for about 10 minutes without any errors and then ran 3D06 fine. Sadly, there was not much a performance increase, only about 100 points when comparing 550/800 and 550/900 so I have to find a way to get me core clock up to begin getting steady increases again.

What kind of volt mods are available for this card? Pencil mod, BIOS flash, etc? I might need to replace the cooler because I don't think the NV6 was designed for intense overclocking as I'm already loading at 65C-70C and want to keep final temperatures under 75C, but I'll see.

Thanks.
 
Some GS's are just better than others. I guess I got lucky, as I don't think I've seen anyone with over 620 without a volt mod. I really need to switch to something other than coolbits for the OCing as the highest the memory will go is 805 and I'm quite sure I can get it higher as I have no artifacts at this speed.

There is a pencil mod for memory voltage and a conductive ink one for core voltages. (I just bought some ink today myself to do those).

http://www.xtremesystems.org/forums/showthread.php?p=2253925

The top post has all the info you'll need. Good luck to us both and happy volt modding :D


EDIT:: Another thing to check if you haven't is if you have one of the rare BFG cards that has a 7900GT core with a few pixel pipelines hardware masked. If you do a search in the forums here I know it was being discussed at one point.
 
If you are going to vmod your card, make sure to get some ram heatsinks and put them on the IC's in the corner closest to the memory volt mod area. They get really really hot and if I don't sink them and put a fan blowing on them, I get frozen screens and flickering.

I am running 1.55 through my core and 2.20 through the memory on water. I am stable up to 710 core and 960 memory.
 
I started goofing around with ATITool (I'm familiar with it after using ATI cards for years) and got my memory up to 900 artifact free. I found I'm getting a bunch of single pixel artifacts (That I can't see in games) at 620 core as well.

I know I could push the entire thing higher before I start to get anything locking up, but I'd rather keep it artifact free.

Having to use .3v more to go from 600ish to 700ish seems like a lot more voltage for not a lot of gain. I'm not sure if I'll bother to go over 1.3, I may do 1.4 but doubt I'll go 1.5 since I'll be using air cooling of some sort.

I'll be doing the 1.3v mod either tonight or sometime tomorrow. I'll post in here what I get out of the card after I do it.
 
Sounds good. I was also thinking about the 1.3V mod as well, hopefully that'll push me to 600MHz+. Maybe I'd go for 1.4V, not sure. I know those very high clocked XFX models have a higher then standard 1.2VGPU which mine is running off but those also may be cherry picked.

Since the only thing I'll need to mod is the VGPU since my memory is ok, is the silver ink removeable? Just incase I try 1.3V and decide I want 1.4V or something else.

And about the BFG 7900GS->GT, I wrote down G71-NR-A2 which was on my chip (or something like that, currently at work so I don't remember off the top of my head) and that pretty much means GS but the only real way to find out is try to unlock the extra pipes. I'll try that later on but as of now I'm just interested in overclocking.

And thanks for the tip thesonofx - do you think VGA-RAM sinks will be enough? I do have a few extra of those lying around but I'm not sure if I'm up for ghetto mounting a fan. Oh I'm not modding the memory I'm happy with 900+MHz. The gain just isn't worth it because earlier I did not see too much of a benefit increasing from 800 to 900MHz unless I can get the core clock up as well, so I'm guessing this will not apply to me?
 
I've been told Acetone will remove the trace you make with the ink stuff. As for the GS->GT iirc the core was labeled to be a GT core.

The various voltmodding guides generally said the chip next to the memory voltage area only needed to be cooled when overvolting the memory.

The link I put up earlier has a picture where a guy circled all the things he found to be getting toasty, but he was also running at 1.5v.
 
Ok good to know. I went out and got some conductive ink so I'll be modding tonight!

Also - where are the ICs located? Figured I might as well throw some ram sinks onto them since I'll be pushing the memory very high (even though without a volt mod).

Edit: Just did the 1.3V mod and I can go over 600MHz on the core now, which is exactly what I wanted. Card is getting to a nice and toasty 70C so I won't be adding more voltage, at least not during the summer.
 
Nice bump in the clocks from the vmod. I'll be doing mine tomorrow night as we're having a party on Sunday and I want to make sure it has time to dry all the way through before I turn the card on again. I'll post back Sunday night with the clocks I'm able to get with the mod.

Look in the link I posted above a few posts down from the top. Picture of a blue card with circles on it for what to sink.

And of other note...
I was just messing with my heatsink (stock eVGA one) and took the shroud and fan out and attached an 80mm to it... What I figured would lower temps now has them up to 50c idle... Guess it's time to undo that...
 
nice results! you're right though. g71-n is gs core. oh well, it's still extremely capable. I'm putting 1.5v to my core and stock volts on ram and running 700/800 with geo delta of 60. Previously, I volt modded from 2.0 to about 2.2 and did 880, but it wasn't worth it. Besides, like mentioned, I didn't cool the vreg ic for mem and eventually got a little flickering.
 
ziddey said:
geo delta of 60.
Click to expand...

How did you adjust that differently than based off the core frequency?

I read an article pertaining to the 7800GT as I had never heard of the term before. But all they talk about it how different things switch at different times and such. So I'm wondering how it can be changed and if it gives enough performance gain to be worth fiddling with.
 
I don't think I noticed much difference. I found max clock with stock gd of 20. Then I set gd to 100 and found the new max. From that, I calculated the appropriate gd to set to get maximized clocks all around.

I think I saw about 200 points extra in 3dmark03
 
Nice overclocks.

I have an XFX 7900GS that runs at 480/1400 stock and I was really impressed that it'll hit 611/900 before artifacting.

Has anyone ever managed to unlock a GS to a GT? Would this be accomplished via a BIOS flash or through Rivatuner?
 
So far only a few BFG cards have been found to have GT chips on them. It's a rare thing to have and the pipes can be unmasked in rivatuner or the bios flashed. But most GS's use GS cores that have the extra pipes laser cut or something so they don't exist.
 
Tried using Rivatuner to unlock and the computer cycled on and off a few times, and when it booted into Windows I still had 20 pipes - so no GT for me. I doubt anyone gets a GT now. Are GT still even in production? They seem to be hard to find now, but the GS is still pretty easy to find.
 
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