HD7950 performance decrease on overclock above 925 stock OC.

Single Infinity · February 11, 2014

So I've had my Powercolor HD 7950 (http://www.powercolor.com/us/products_features.asp?id=455) for maybe a year now, and for the most part I've been satisfied with performance. Lately I am trying to play Far Cry 3 again, and with everything maxed. but AA off, I can get 55-60 stable. I figured I could overclock a little to try to get headroom for some AA. This is where it gets confusing. The card ships at a base of 925 Mhz on the core. That's not bad, since the default is 800. I run heaven to bench in some places and watch my frame rates.

In the first space in Heaven 4.0 I get 21-22 fps with my particular settings. As soon as I increase my core clock at all (5,10,15,25 Mhz) my frame rate drops in that same area to 17-18, and 26-28 instead of the 31 average from before in the next area. I've read of many many 7950's easily reaching past 1100 Mhz(sometimes without even touching the voltages). Anyone have any ideas why I can't even go higher than 925 without lessening performance?

AlwaysFSX · February 11, 2014

Maybe it's unstable? My 7770 is stable at 1095 but at 1096 all hell breaks loose and I lose performance and everything crashes.

Single Infinity · February 11, 2014

Any other help? I don't think I would need to touch the voltage at this point, considering most can get well over 1000 Mhz before they ever touch it.

February 11, 2014

Any other help? I don't think I would need to touch the voltage at this point, considering most can get well over 1000 Mhz before they ever touch it.

Well, no card is guaranteed to overclock. All you can expect is that it will perform within spec; beyond that all bets are off, unfortunately.

Some suggestions...make sure that the card is cooled adequately and receiving sufficient power for overclocking. Make sure that your OC is actually increasing the clockspeed beyond stock. Just for fun, try larger offsets, such as +100MHz.

SlaughterSmurf · February 11, 2014

Silicon lottary my friend, hell I have lost the lottery so hard I got a 7970 that was unstable at stock, then the replacement ran at 100 degrees at stock.

Face2Face · February 11, 2014

So I've had my Powercolor HD 7950 (http://www.powercolor.com/us/products_features.asp?id=455) for maybe a year now, and for the most part I've been satisfied with performance. Lately I am trying to play Far Cry 3 again, and with everything maxed. but AA off, I can get 55-60 stable. I figured I could overclock a little to try to get headroom for some AA. This is where it gets confusing. The card ships at a base of 925 Mhz on the core. That's not bad, since the default is 800. I run heaven to bench in some places and watch my frame rates.

In the first space in Heaven 4.0 I get 21-22 fps with my particular settings. As soon as I increase my core clock at all (5,10,15,25 Mhz) my frame rate drops in that same area to 17-18, and 26-28 instead of the 31 average from before in the next area. I've read of many many 7950's easily reaching past 1100 Mhz(sometimes without even touching the voltages). Anyone have any ideas why I can't even go higher than 925 without lessening performance?

Have you tried any other benchmark test other than Heaven? The 7950 responds very well to overclocking. You have the Boost model, which means your stock voltage is 1.25v. You should be able to hit 1100Mhz without even toughing your voltages and your performance will increase. Make sure to overclock your ram some as well.

Single Infinity · February 11, 2014

After doing some more tests, I can finalize that I have lost the silicon lottery. :c I OC'd ~25 Mhz up, and even pushed my voltages a couple percent higher, with loss in performance, and I also underclocked to see if the factory OC was too high as is. Seems like 925 is the peak for my card, which happens to be what it shipped at. Seems odd and less lottery-ish that my card is in it's exact highest OC point from factory. Maybe Powercolor OC's cards as high as they go and markets them from there? =/