Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to clean a cpu fan [title] Shut down your pc and turn the power off. [step] Remove the power cords from the rear of the tower and disconnect them from their power source. [title] Place the tower on top of an anti-static mat that has been laid on top of a table.

Ending1: [title] Unscrew the screws holding the tower in place. [step] These screws may not work immediately because you may need to cut some threads that may interfere with the screw. Ending2: [step] You may also wear an antistatic wristband that is connected to an electrical ground, like a metal plumbing fixture. You'll need to use the antistatic devices because static discharge from the floor or from your body could damage data stored on the computer. Ending3: [step] Make sure to remove the connections between the wires to make sure they are completely free of any metal tension. [title] Place the tower through the x-bolt hole on one of the battery terminals. Ending4: [step] You will find this mat where you will place the fan into place. [substeps] Turning off the main power source will help prevent friction, which is likely to occur when testing out your motherboard.

Answer format: ending1/ending2/ending3/ending4