Power supply fan not spinning but still works, what can be wrong

Solution
http://www.amazon.com/Corsair-CMPSU-650TX-650-Watt-Series-Certified/product-reviews/B000X24ISU

One of the reviewer say "Also, this thing has a fan that, by design, does not always run. The fan will briefly come on at initial power-up, but after that will only come on under certain heat/load conditions. Nothing I did -- running 3DMark, playing Crysis with all graphics setting maxed -- caused the fan to come on again. Perhaps my case is better cooled than I realized, or perhaps I was drawing less load that I thought. But it seems like it's gonna be pretty hard to tell if the fan breaks if you can't even tell when it's supposed to come on in the first place."

sonexpc

Honorable
Feb 20, 2012
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http://www.amazon.com/Corsair-CMPSU-650TX-650-Watt-Series-Certified/product-reviews/B000X24ISU

One of the reviewer say "Also, this thing has a fan that, by design, does not always run. The fan will briefly come on at initial power-up, but after that will only come on under certain heat/load conditions. Nothing I did -- running 3DMark, playing Crysis with all graphics setting maxed -- caused the fan to come on again. Perhaps my case is better cooled than I realized, or perhaps I was drawing less load that I thought. But it seems like it's gonna be pretty hard to tell if the fan breaks if you can't even tell when it's supposed to come on in the first place."
 
Solution