Firstly make sure your drivers are all up to date. That may be a simple way to fix the issue.
As for the high temperatures: if you're no longer under warranty, open up your case, and take the video card out. Make sure you ground yourself first (anti-static bracelet if you have one - if not google methods of grounding yourself) as you don't want to damage anything. Once the card is removed, clean it and add some more thermal paste to it. Make sure your fans are all spinning fine and aren't all clogged up with dust (best way to remove dust is bottles of compressed air - DON'T use a hoover.) Once this is done, put the video card back in, and wire it all back up. Then try again, and see if the artifacts are gone. This is by no means guaranteed to fix your problem, but it may help. Be careful - if you mess things up more then you've got no one to blame but yourself Just make sure you put everything back exactly as you found it, and you'll be fine.
Have you overclocked? That may have caused this issue if you have. Regardless of whether you have or not, it sounds like you'll need to underclock to reduce the heat generated by your system if the above methods have failed you. Get Rivatuner to help with this - the instructions are pretty simple. You'll lose some performance at the end of the process, but it's a choice between performance loss or artifacts. As per above, this may not necessarily fix the issue, but if the other methods have failed then you could try this. Again though, be careful playing around with the clock settings, even with RivaTuner. Make sure you make notes of all the numbers, so that you can edge your settings back up to where they were originally should you ever want/need to.
I have not overclocked anything, and all drivers are up to date. Which makes it alittle more frustrating.
I took it to Fry's who originally built it and am having them put on a after market heatsink (212+). The CPU temps are the ones that go over the recommended amounts.. the GPU temps have been fine.
Regularly the CPU temps go over 65 C, and during Battlefield BC2 they have gotton into the high 80's C. I ran Prime95 for a minute just to see the temps. The CPU cores were all mid 90's... crazy.
My case has great airflow.. Only downside was I used the original heatisnk that came with the CPU (the techs talked me out of a after market one). Still though, I don't think I should get that crazy of temps.
I made sure they would use the after market and the arctic silver 5 I had... We'll see if it makes a difference. Hopefully so.
you may also wanna try turning physix off if you have an nvidia gpu just to test its not that part of the gpu wobbling.
also if your gonna start using thermal pastes. use the better 1s like mx-4 over AS5. mx-4 has no cure time, while AS5 can take 200+ hours to get your temps stable and they wont be as low as the newer brands.
as5 is very much middle of the road today as far as tim's go and not really worth the money when you can get better cheaper...
I'd always advise after market cooling for any gaming PC. 90c is just too high, there's no two ways about it.
Get yourself a good CPU cooler, and some additional fans (they're like $12/£9 each for the small ones) and stick them in there as well to help with air flow (get a push/pull system going if you can.) Then I'd just say that every 6 months or so you need to open up your case and blow dust away with compressed air, and your PC should stay nice and cool. If temperatures start to rise again, one of the first things you do (besides clearing dust) is to put on some thermal paste, as it's actually more effective than people give it credit for