Computer fan won't turn on.?

>It could be the motherboard battery, a flat CR2032 silver battery needs replacing. Locate it on the motherboard in its own recepticle or socket. use a small flat head screwdriver to depress it from the clip and it will pop out. Go to any drug store that sells CR2032 batteries (take the old one with you), buy a new one, pop it back into the slot so it clicks in place and if this is the problem, it should boot normally. You may have to go into BIOS and reset the primary boot or first bootable device to your hard disk.

If this does not do it, it is most likely the power supply itself. A power supply can still be half alive and provide enough power to turn fans or diodes on, but not enough to kickstart or operate the computer with. This is your next step if the battery fix fails to solve the problem. Replace the power supply with a new one.

If the fan spins up and then stops, the problem is NOT the fan. The fan is turning off because the computer is turning off.

Depending on your level of computer knowledge, I have two courses of action:

1) Take it to someone who knows how to fix computers

or

2) Remove all non-essential hardware from the computer (any removable card besides your video card, your network card, your hard drives, CD-ROM drives, etc) and see if it boots - try removing all RAM except for one stick, and then change which stick you're using. If you're not even able to POST, then you're most likely looking at a hardware failure of your CPU, RAM, motherboard, power supply, or video card.

after doing that... check to see if all the cards and additions are seated correctly.

buy a can of compressed air and spray the inside of the whole computer. You may have a dust build up.