OC 7970

[BTC guy]

I just got a few 7970 to play with. Im getting 640 hash but i cant get core stable past 1080. Cant drop memory below 900. And im not sure if CGminer or trixx is controlling memory and volts. When i adjust with trixx it shows changes within trixx but not within CGminer. Who here has already played with these and can give me some tips? I hear people talking 1150-1200 core and 700 hash. I would like to get that too if possible.

[cmg5461]

use afterburner.

Lowest I've gotten mine is .949v ~ 1000mhz w/ 710mhz memory ~ 580mhash/s

Voltage won't change in cgminer.  It's bugged.  Use Gpu-z to verify the voltage.  Also read the asic quality of your 7970's, as that will guide you with overclocking

[BTC guy]

Darn i thought i was done with these third party OC tools when i started using CGminer. Thanks for the tip will check out afterburner again.

[BTC guy]

Now running 1125 core 670 hash. Gonna try for 700.

[BTC guy]

Was running 1200 core 720 hash.

[cyberhelix]

Now running 1125 core 670 hash. Gonna try for 700.

I have seen 689 out of mine before... everything maxed out. (1125/1375)

Good luck on the 700

DiabloMiner Rocks!

[phorensic]

Just like my 5830's I had a few hundred hours at top speed on my 7970 at a glorious 1200MHz core.  Ran a few more weeks at 1175, now I'm down to 1150.  It's the crashes in the middle of the night that I don't catch until I wake up that kills the profits.  Which means it's better to run at a lower core that is more stable than try to eek out that last 5MH/s.  As far as voltage, every time I cranked up voltage I had diminishing returns on clock speed while power usage and heat skyrocketed.  I don't recommend touching the voltage.

[BTC guy]

Your right. I just wanted to see what it could do. I have it running 1100 no volts. I might put a little extra volts for 1150.

[AzN1337c0d3r]

The 7970 is incredibly efficient when undervolted but cranking up the voltage does almost nothing for clock speeds and power usage skyrockets. This is due a fundamental physics phenomenon which is related to the way we design transistors and the shrinkage of distance between source and drain called subthreshold leakage.

On a more practical note: My pair of 7970s can hit 1125 MHz at stock volts and generate about 1350 MHash/s.