I know there is a topic that addresses this already, but I have some computer-specific questions related to the procedure/advice that is given in the other thread. I have a IBM ThinkCentre 3.0Ghz machine that is randomly shutting itself off. It appears to be an overheating issue. The other post recommends checking the fans. I see two fans in there (they both work), but does anyone know how many fans there are in this machine (it's a tower). Is there a hidden fan that isn't working or is it just the two I can see? Second, if the heatsink has a thermal pad, do I still need to apply a new layer of thermal paste? Third, what temperature should a computer run at? The other post included a link to a diagnostic tool, but I don't have any benchmark for comparing my computer. Also, if the computer shuts down when it gets hot, how can I use the tool? Thanks for your help!