I have to unplug the power every time before i start the com

i installed this computer myself. after a while, when i push the on button, the computer's cpu fan will make a really loud abnormal noise. and the computer screen won't even light up.

so i have to unplug the power inside the motherboard, then unplug the power outside the computer case.

so what is going on here? I won't mind doing it, since i have the case open all the time now. i am just wondering if the computer will last as long as those normal computers?

thanks.