When you mean fan, do you refer to fan on motherboard or power supply fan?
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If none of the fans worked, turn them off immediately. You don't want your computer be toast because of stupid overheating.
Have you checked all the cable from power supply to your motherboard? There are 2 main cable to take note, the 24pin (large one) and 4pin (yellow and black cable) and make sure both of it connected properly to the motherboard. If still none, unplug it and plug it back afterwards.
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Ok lets troubleshoot a little..
First unplug all cable connected to your motherboard, power supply, HDD, SATA cable and DVD-Rom and even RAM. (except cable from your casing)
Then plug in only power supply cable to your motherboard (2 cables) and turn on your computer. If it beeping about three times plus all fans working, then put back RAM and see if the beep still there and observe the fan as well.
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Then it's your power supply problem. It only have enough power to light up LED but not the motherboard itself. Consider buying new power supply for your desktop or if you have old computer or other computer that you use, try to salvage it for a while and try it on the faulty computer. If it's on, then most likely your power supply is dead.
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