If a computer won't startup at all, what is the most likely issue, and is there any way to find out FOR SURE that it is one component and not multiple components? A friend of mine's computer won't start anymore. No new installations of any kind, hardware or software. just won't start. I tried taking everything out except mobo, RAM, CPU, and PSU. still nothing. I thought power supply at first but the ALL fans work (the PSU fan, cpu fan, and even fans that are directly attached to the motherboard.) Also I get a light when i push the power button. Soooo... I believe I reduced the chances of it being a PSU, and maybe even the motherboard (since the fan attached directly to it works?) Can it be the RAM or CPU? How can I know for sure? Or can it STILL be the motherboard/psu?? It's not a grounding issue since I took everything out including the power supply and tested it static free outside the box.