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Overclocking crossfired XFX 7950s - Not sure if I'm reaching full potential

post #1 of 4
Thread Starter 
Hey guys,

So I've recently just finished 'The mod' which has dropped my temperatures significantly (http://www.overclock.net/t/1203636/official-amd-ati-gpu-mod-club-aka-the-red-mod/1520#post_20551151). The cards I'm using are XFX DD 7950 (800 Mhz, 1250 Mem stock).

So far I've managed 925 core 1350 mem @100% Load and I get max temps around 57 degC for both cards. I can't control voltage on MSI AB, however according GPU-Z my voltages are around 1030 mV. It seems raising the core any higher results in crashes and lockups (when running Heaven 4.0). I also believe these cards are voltage locked. Does anyone know a way of unlocking the voltage?

I'm just wondering if I'm missing anything crucial when OCing crossfire configurations. I'm aware that maybe disabling ULPS will help, can anyone confirm this? Does anyone have experience with crossfire + OCing on these cards? Any insight into how I can improve the clocks would be greatly appreciated!
post #2 of 4
No voltage unlock, but you can flash a vBIOS to the card with different voltage tables/settings that may get you where you want to go. I have a pair of XFX 7970 DD cards in xfire and, although they are not the 7950s like yours, should be similar enough to equate experiences.

I've MOD'ed one and the other still has the stock cooler on it. Even after The MOD, my primary GPU temps were uncomfortably high (note that they were MUCH better than prior, re-seating the the Antec a couple of times was necessary).
That 7970 had come from the factory with a vBIOS running 1000Mhz core and 1425Mhz memory. To compound the problem, it was set to run at 1.125v at all times, 2d or 3d clocks. Even idling on the desktop at like, 300Mhz produced unsettling amounts of warmth.

So, TLDR, I grabbed a stock vBIOS for my XFX HD 7970 DD from Techpowerup.com (iirc) and flashed it to my primary. Now it runs cool (with the MOD) and actually overclocks better since it's not on a forced 1.125v lava-rocket-power setting. (fyi - volts still scale as normal with use, up with 3d clocks, down with 2d clocks).

What I'm suggesting here is, maybe you want to look for a vBIOS that you can flash to your 7950s that has slightly higher voltage settings to get better overclocks if you're not stable at the clocks you're trying for. It won't unlock your cards per se, but it's kinda the next best thing.
post #3 of 4
Thread Starter 
Thanks a lot for the info. This is something I have never considered and I'm not really familiar with flashing BIOS. Do you know of any resources guides that may have helped you understand the topic and process? Also, which bios did you end up going with? Did you stick with one of the XFX ones?
Edited by smacchesney - 8/8/13 at 9:11am
post #4 of 4
I used a vBIOS from techpowerup.com that was listed in their VGA BIOS database. When deciding one which BIOS file to use, I tried to match my model and revision closely (XFX R7970, FX-797A-TDFC, Double D). And then looked at the clocks and voltages listed in the file details. Their database is pretty outstanding.

As far as the flash process itself, I read through a few guides and step by steps online. There is a great one here at OCN in the main ATI/AMD Graphics Card Forum. Though I don't have the link handy.
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