It's going to depend on several factors, but if it's sitting idle and running at more than 40 degrees C, I'd consider better cooling and/or a better heatsink.
Contrary to popular opinion, removing the side panels doesn't always improve the cooling. I'd start by making sure that your processor heatsink is properly mounted with thermally conductive compound, and the fan is working 100%. Next, I'd make sure there is plenty of airflow through the case, my current P4 2.4ghz machine has three case fans, one for the P/S, and two others. You can't have too much cooling, but you can have too little.kamjack said:Hmm, well I'm running 50-55 degrees celcius running pretty hard 24-7. Ill remove the side panel for now untill I get more cooling, thanks for the info.