wd40 won't 'fix' bearings that have gone bad and a bad fan can cause overheating which can ruin the board components.
My graphics card fan was broken so my uncle fixed it and put some wd40 oil on it. It worked perfectly then after10 hours of playing half life 2 my computer just shut down. there is no orange light so i thought i was okay. I open the computer and take out the graphics card and put oil on the fan. I put it back and turn my computer on. All i hear is this one short beep as i turn it on and my fan and everything is working perfectly but the screen is black.