GPU overclocking and core clock fluctuations and mem ratio

[trueimage]

Hi, just got 2x 6950 2GB already flashed to 6970 unlocked shaders

I am running GUIMiner with flags -v -w128 -f 0
I am running drivers 11.5b
Win 7 x64
Stock speeds on these cards are 800 / 1250

I've got two copies of GPU-Z running and they show a solid 800 mhz, 99% load, 1.1000 V

I installed MSI Afterburner, and the max it allows me for clock is 840, so I set it to this and tried every voltage up to 1.2000 V

The problem is that the clock speed fluctuates in GPU-Z down to 792 MHz and back up to 840 and a few in between. Is this because there is not enough voltage to keep it at 840 under 99% load?

I bought these from a friend and he had them under water cooling at 925 / 1250 @ 1.3v

Ok also, I've read a few posts about memory speed doesn't matter so clock it down to save power / heat / etc. And I've read references to using a ratio gpu : mem clock. Any tips on this?

Cheers.

[gigabytecoin]

If you can underclock the mem to 300mhz... you can probably squeeze 950mhz out of the core! Good luck!

[accod]

Open CCC and in the Performance section set the Power Control to +20%.  That should stop the fluctuations.