I know that it sounds really trivial, but check the power (voltage settings) in the back of your psu. I once heard someone had the 220 European set instead of the 110. Same thing was happening, fans powered up then went back dead...
Also, did you smell any burning smells? Maybe your cpu burnt out? Just a thought. Try taking out a single component and trying, ie your memory then next time try your hd, then try swapping vid card, etc.
i am a student of diploma in electronics and telecomm
can anyone suggest me projects related to the below domains:-
electrical and electronics