I accidently put the Fan on my 2500+ barton processor the wrong way. I had a different heat-sink on there, a nice one, but the wiring on it was poor and it pretty soon stopped spinning. So I put the stock fan on there, and I accidently had it on backwards. Lucky, my motherboard noticed this and turned off the machine. At first, I couldn't tell why, Then I noticed that my fan was a little askew, and that it was turned the wrong way. No damage to the processor tho, at least I think so...