Overclocking is like stealing from the GPU manufacturers. Why would you think you deserve vastly improved performance, without having to pay for it?
If you want your 7950 to run like a 680, you should make a donation to AMD and NVidia for stealing that extra performance.
Ahhh . .. If "the subtle is sublime," then you're either making a good joke . . . or . . . What?! Are you crazy?!
You're stealing from yourself -- technically voiding the warranty, which you paid for in the purchase price, and possibly even shortening real expected product lifespan. And I could be crazy, too, for even bothering to post this . . . Fun and games . . . Fun and games . . .
Well, back to the question. It really didn't seem to make a big difference for my 8800 GTS. Instead, my inexperience caused me to misjudge stability. About once every couple weeks, the system would blue-screen, and I would troubleshoot about everything else and overlook that the RivaTuner or whatever was still installed on the system. I finally figured things out after choosing to review the 8800 GTS BFG product spec -- even verifying from my original sales receipt.
So I reset the damn thing to defaults and lived happily ever after.
I'd only guess you can get more noticeable performance improvement through over-clocked SLI, but it would seem to be a lot of trouble.
I've got the dated last-gen 570 GTX. I just don't see the need for the extra power consumption, when weighed against performance. I play a limited set of games, but I don't think I'm encountering much in the way of full CPU load or dropped frames . . . .
I"m happy . . . .