<endlurk> Apologies if I'm late to the party, but I wanted to add that spinning the fans too fast in either direction can damage them. <resumelurk>

Right you are, although that's less likely with canned air. Welcome to ETS!

Do folks really stick paper clips in their fans at night when they turn off their computers? I never turn mine off, so it's not an issue for me. This is not something I would have considered doing though. I can't imagine the slight, if any, rotation a powered down fan would encounter would be anything to worry about.

This only applies when using compressed air to blow dust out of the machine.

Ah, OK. I've shot compressed air into my fans many times. But I hold them still with my fingers, because it doesn't work trying to blow the dust off a spinning fan. Still, I never knew that it would damage the fan. I'm sure I've lost my grip on the fan blades in the past and one has gone spinning under compressed air. Oh well, I just replace the fans when they quite working. For most of my fans, they have kept working a phenominal amout of time. But occassionally one will give up the ghost. Usually it's one of the small oddball sized ones that you have trouble finding local replacements for, and have to order online. Like the 50mm and 60mm ones.