I recently upgraded my system --got a 580gtx (from 460gtx) and required 750W psu to run it--only to find that if anything, Skyrim was running WORSE than before. A wtf if there ever was one. Not only were my framerates actually worse but my computer also developed a habit of abruptly shutting, well, off. Not fun. Well I figured it out and thought I would share my experience to save some of you some trouble should it happen to you. Updated my video driver, nothing. Played with my Nvidia settings, nothing. Then I thought to myself : well with it shutting down like this maybe it's a heat issue. So I did some asking around and ended up getting a program called Speedfan (free download, no adware,I'll look where I got it if anyone wants) that monitors temps in your system wherever there's sensors to do it. Well I cranked up Skyrim and sure enough after a couple minutes my CPU temp was at 85C or about 187F I think. Way too hot, turns out the new 580gtx actually vents its heat into the case interior instead of out the back which doesn't help. So i look at the heatsink, all clogged up with dust. So i did 2 simple things: took canned air and VERY carefully and with short controlled bursts (I'm not joking, static will build up and fry things if you're not very careful) and blew the dust out of the heatsink and went into the bios and set the CPU fan to run at minimum 87.5%. It now runs nice and cool. But the point of all this is the HUGE performance hit I was taking, my fps are silky smooth on ultra now. If you have fps issues & don't know what temp your cpu is running, find out.