I have a GTX560 and an AMD II X4 965 @3'4ghz. As many people reporting here I had huge FPS drops aswell, it was ok at times with 60 fps but then it would drop even at 10 inside towns for a long while. I did 2 simple things and now I have constant 60 fps EVERYWHERE with almost everything maxed out. First I downloaded the 285.79 beta drivers (you gotta search for those, they don't appear if you use that automatic tool on the nvidia website). I also have cool 'n quiet active (AMD feature) so my CPU don't use full power when I'm just in my desktop, for some reason some applications fail to make the CPU use full power so in the control panel I changed from "power saver" to "balanced" and that's it, now the game runs perfectly with no problems at all.

I hope this can be useful to someone with a similar setup having fps problems.

How do you see your fps in game? TDT doesn't seem to work anymore.

I use Fraps for that, very easy to download and to get it running.

Do you know an Intel equivalent to Cool'n'quiet?

No sorry. My problem here was that Skyrim didn't wanted to use my CPU full speed because of cool pn quiet was set to saver mode. if your CPU is running at full speed the whole time you shouldn't have a problem.

If you're running Windows 7, go to: Control Panel->Hardware and Sound->Power Options and select the High Performance option. It does the same thing. Hope it helps.