TweakTown posted an article on NVIDIA GeForce GTX 480 Overclocking with Voltage Adjustment. Here's a taster:

The first thing we have to say is that this isn't practical. When we say that we mean it's not practical in the sense that you cannot have the fan running at 100% when you're gaming; honestly 82dB is loud. I mean - it's really loud!

If you go down the path of water cooling the model though, you're not going to have this issue; the other thing is because we ran on such a tight schedule and AUTO didn't want to play nice, we just cranked it to the top. To be honest, everything might be sweet at say 70%; of course that's something that you can find out without any real issue.

Performance is insane! There are some absolutely massive gains seen especially at 2560 x 1600. Some of the most noteworthy scores would be a P25k run on a single GPU air cooled video card and almost P26k in our suicide run. V2 Heaven outperforming the HD 5970 and the GTX 480 going from matching or being behind the HD 5970 in H.A.W.X. and RE5 AA benchmarks to being clearly in front.

If you had to put it all in perspective our TPR graph paints the best picture; we've gone from 42,514 to 49,027, which equates to an increase of over 15%.

There's no denying that NVIDIA had some issues with Fermi; what this shows us today though is the potential. The next generation of NVIDIA videos cards I think will be a force to be reckoned with.