Quote Originally Posted by The-Fox View Post
I had walked the path of OC with the 4870X2 as well.
I managed to OC it very well I think, both cores benched 3DMARK06 and Vantage @ 880/1080.
The slave core was quite stunning alone and managed to bench @ 907/1125, but when both cores were OCed I had to lower the clocks as it wasn't stable.

I own the Sapphire card, flashed it with the 900/1000 limit using the RBE tool (not the ASUS Top bios).
I tried to raise the voltages to 1.35v, as it uses 1.25v (GPU-Z shows 1.265) in 3D mode, and 1.05v (GPU-Z shows 1.06v) in 2d mode.
Unfortunately that didn't do it and the card was still getting 1.25v, so it appears to have no effect in reality.
I then Overclocked the card using rivatunner, each component at it's own time, meaning GPU#0 memory, GPU#0 Core, GPUE#1 Memory and at last, GPU#1 core.
After all that I gave the card a few runs with 3D 06' and eventually came down to some stable and benchable clocks.

I use the EK block to cool the card, so far it has amazing temps (below 40c) even under OC.

binormalkilla, you need to disable CCC at the startup (use msconfig) as sniiipe suggested.
Otherwise you won't be able to Overclock beyond the bios limit (800/1000), CCC checks for the clocks in realtime and if you go above those clocks you get the card unstable/artifacting.
Right, that's why I flashed the TOP BIOS, which set the CCC limits to 900/1000. I may try disabling CCC if I can get it stable past 900 in Vantage, but I'm not 24/7 gaming stable at 862. I would like to raise the memory OC limit though, as the TOP BIOS only allows 1000 in Overdrive.

I wonder if a BIOS flash past the Overdrive limit will cause instability?