Recently I started to have a problem with my (4 year old) stock cpu cooler. When I start the computer, the fan might not spin at all but twitching. Looks like it tries to spin. So what I do is I restart the computer, if that doesn't help I unplug the 4pin from the header and simply put it back and then it works normal again. But I wonder why I have to unplug and plug back almost everytime for it to work? Is the problem in the cooler or somewhere else? I have i7-3770.