Often. A suspect list that can create your symptoms is quite long. Other posters have listed a minority.I never said it was the psu, i said it could be, but it could be also the motherboard and hence why im asking here to see if any others have had similar experiences.
An answer without speculation means multimeter is the only way to obtain that answer in the next reply. Even PSU testers are useless.
Long before the CPU can execute, the power controller makes numerous decisions. Your post could be saying it reboots before the CPU is allowed to work. Or after. All those decisions, even long before the BIOS executes, is decided by the controller.
Of course, if the CPU does not execute, then CMOS is never read. First the controller makes many decisions. Then the CPU is allowed to execute. Then the CPU executes the BIOS. Then the BIOS reads CMOS. None of that happens if a power controller forbids it.
Remove all RAM and the video card. If the motherboard does not beep an error code, then the CPU is not even executing.