Psu+mobo+cpu/hsf.
Nothing else connected.
If it still tries to power up as soon as you plug in the power cord your down to 3 parts.
When I plug in the power cord to my pc the cooling fans will turn on ,pcu cooling fan will turn on, and it starts to turn on but instantly after 3-5 seconds it'll shutdown, I realized I didn't have the sata data cables plugged in,Can not having the data sata cables plugged in to your hard drive and mother board cause it to shut off or is there another reason? (this is a brand new pic with new components never been fully booted up haven't even installed the os because of this issue)

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