PC shutdown fans still randomly spin

[szilyke]

So I shut down my pc but the fans still randomly spin from time to time , inclusind the cpu fan . But this isn't even the worst part , this happened twice and the second time I couldn't turn my pc back on. What could be the problem ?

 

[TheVrolok]

I would guess, in no specific order, power supply, motherboard, or poltergeist.