I recently replaced the motherboard, CPU and LCD screen in my Inspiron laptop N5010, it is working perfect but when I turn the laptop on the fan inmediately comes on even though the laptop has been turned off for a while so I don't think is a heat issue, I have heard that some CPU's  are bigger than others so because I replaced it (I had a technitian back East do it)  perhaps with a bigger CPU is causing the fan to come on, I asked the tech about it he says in some laptops it is normal, he did not seem to be worried about it, any suggestions? Should I leave it alone?