Ok, I tested with the side cover off, with and without a fan. Here's what I did and what happened:
1) Cover off, fan off. Ran around Orgrimmar for a while but wasn't getting any glitches. Ran out into Durotar, lots of spinning around etc, started to get major graphical clitches. I switched on an external mains-powered desk fan, on full power, drenching the graphics card and RAM ('tis a big fan) in cool air, but the glitching continued.
I cycled through windowed mode and back to maximised using ctrl-M or whatever the shortcut is. Everything back to normal
2) Cover off, fan on full. Continued to run around outside, lots of intense spinning around and using the mouse to rapidly look about. I was unable to recreate any glitching. I switched off the external mains-powered fan and after a few seconds heard the fan on the ATI card spin right up. I kept spinning/running around and a few seconds later graphical glitching started again.
Now, I'd have thought that when I got the glitching the first time switching the fan on would have fixed it if this was an overheating problem? Or perhaps the UI needs to be refreshed before that's possible? Interestingly when I had the fan on after that glitching didn't start again until I switched it off - but I'm no scientist and perhaps my little experiment was flawed.
Anyway, I hope that helps somehow. Please fix this horrible problem
