Just thought I'd put in my .02 on mining with the 480's.
I have my cards set at 1333Mhz Core clock, 2100Mhz memory. I noticed that for some reason, my Powercolor Red Devil 480's actually throttle at 80C. I really have no idea why, and I was only getting like 190 sol's, tops. And I noticed my core clock and voltage were dropping.
Only when I applied a really aggressive fan curve, and kept my temps down below 80C, more like 78C, was my core and mem clocks going back to where I set them. At that 1333/2100 I'm getting about 203 sol/s per card. So do be sure to check that out in Afterburner, or whatever program you're using. I don't know why they're throttling so low. I do know that they never even came close to 80c when gaming at stock fan settings, so since this card seems to already run really cool anyway, they may have set it that way in BIOS or something. But just something to keep in mind, folks.
You can always modify the bios with Polaris bios editor....raise the throtling temp, it has very simple user interface, you can done it by without asking for help if you have general knowledge for Computer's.