While the symptom is usually a sign of an overtaxed PSU the reason it may start as you try is that Electrolytic Capacitors work better when warmed up.
So without knowing much about your PC, it's either a stressed PSU or our old friend BAD CAPS.
I would go to turn my Gaming pc on and when it turns on. on my monitor its just a blank screen. I would then try and turn it off, flip the switch, then unplug it wait like 10 secs and I would plug it back in flip the switch and turn it on but it still does not boot up, i do that like maybe 3 times and finally it boots up but if i turn it off it happens again. can anybody help me??

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