When you have The Dead PC (google that) the accepted way to work out what it is, is to reduce the parts until it powers up. If you get down to just PSU and a motherboard (no case!) then you are looking at the two suspect parts.
You omitted age and what the parts are but some PCs do this when the CMOS battery is too low. Can you try a new battery?
Hello guys, my pc won't start so I opened the side cover and then tried turning it on but nothing happened. while I can see the light on graphics card turned on. First, I thought that smps might not be working so I put it into another pc and it worked. I placed the smps back and still when I switch on the cpu nothing happens. what is it?

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