I bought a sapphire 6950 2gb in august, warranty is still good so this is not life or death but I would rather see if it is fixable before enforcing the warranty.
The problem is that when I increase the memory clock, and just the memory clock, beyond stock (even just from 1250 to 1251) if I navigate windows or the internet the display has a black line or two shoot across very quickly or jitters, after this initial jitter the page is 100% fine. *** This does not appear to happen in games, atleast the games I play ***
The true problem is that until 3 days ago the card was constantly at 900-1300-1.125 overclock and completely stable. At the moment it is at 900-1250-1.125.
I can put the card at 900-1300-1.125 and run furmark at 1080p 4x msaa and still get the 30 fps that I got before this jitter crap, and it does not crash. Another question... is 30fps with 1080 4x msaa furmark good for a 6950...
I agree with amuffin. OCing memory does little for performance. In my experience, OCing the core with slight increases in voltage have given me noticeable performance changes. BE CAREFUL WITH THE VOLTAGE!!!!! Im talking .001 to .005 increases at a time. Also, make sure your mobo can handle VDD increases. As with any overclock, if you increase the core you MUST give it the juice to support the increase.
I found a larger issue, my mobo first pci slot was defective, I blew it when I got my 2560-1440 monitor and played on it for a bit. Second pci slot is working, for now, but I am trying to rma the board for a comparable matx board from the same manufacturer.