So i got my gaming Pc about 4 months ago, everythng ran great, i suddenly got a black screen, i reinstalled windows 7, and all of its drivers for the graphics card and motherboard, But i now get a warning everytime i start up my pc about a CPU fan Error!, i have intel i5 2500K, with a Hyper Evo 212 gaming fan, it is going down to about 500RPM, then rises a little bit. Is this unsafe?, should i buy a new fan?