Did a smell of sulfer came out your computer? If so it might as well be your CPU or your memory.
If you have acces to another computer and your a little handy dandy I would ripp the power supply out of one and test it in yours (you can do this by placing them next to eachother and put the cables from the other one into yours, you don't need to screw it out and in yours again just to test it).
Which also can be helpfull sometimes is try another wallsocket... sounds strange but that worked for me on serveral occasions....