Things You'll Need
Instructions
Open the console, and check that the fans are plugged into the motherboard properly. Inspect the connection for any possible errors in reassembly, and ensure that all pins are connected.
Examine the bases of the fan motors, as the solder between the wires and motors can sometimes become brittle and break when the fan is removed or reinserted. If a wire has come loose, resolder it to the proper connection on the motor.
Check for damage to the wires connecting the fan and the motherboard, especially if you are drawing power from the fan cables to run your LEDs, as the connection to the fans may no longer create a complete circuit.
Check for scratches and burn damage to the fan's power connection leads on the motherboard. You may be able to fix a damaged lead by applying solder, but in some cases this is irreparable.
Disconnect the LEDs from the power supply to determine if the LEDs you are using are faulty.