8800GTS Temperatures and my case

[kc_drifter7]

I bought a new PC recently, it's an HP and I believe the number is m8120n. I also purchased an 8800GTS, which just barely fits in the case. When I set the GPU fan to 100%, the card idles at about 63-64 degrees celsius and hits around 78 degrees while running fairly stressful games. However, if I take the side of the case off and rest it on the case, it idles at about 57 and only hits 66 max while playing games.

My question to you is, what's better? Letting it run hotter or risking a bit of dust?

Thanks a lot, I appreciate the help.

Here's a simple picture of how the side is laying at the moment (this is from the front and the side of the case is the blue line):

 

[Shez]

I'm not sure what the interior of your case looks like but it sounds like you could benefit from adding a few more case fans. If your case has an intake fan in the front and an exhaust in the back, see if you can't add side fans or more intake fans. If you can't add more fans, buy fans with better CFM values (although you might risk having a nosier computer).

With the 8800 GTS it will really help to have a side fan blowing cool air directly onto the card/into it's intake fan. Your entire system would benefit from better air flow in general.

Question: Is your room particularly hot?