My laptop fan dosen't spin


Sep 27, 2012
I have an i5 4520s probook without motherboard.First i order from ebay one motherboard,but when i start the pc the fan goes for 2 sec after stop.If the temperature is 90-95 degrees the fan is still dead and the laptop stop because of overheating system safe.I order another motherboard from the same seller.This one was working fine for about 4-5 hours after stopped and the same problem like the first one.Where is the problem??The motherboards are used,no new.I don't have money to buy new motherboard but can be problem from cpu or fan?