Power supply powers the machine and therefore the video card which gives output to the monitor when it is plugged in.
Remember too that because it gets some power does not mean it is getting the correct power.
I am off now, but good luck and don't forget to post back.
Addendum: Yes, you can delete the zip file. No secrets, but you may feel better.
I would not encourage anyone to dump an old PC unless the cost of repair outweighed the value. And if it still meets your needs there is no need to upgrade.
Belarc will not show power supply unit.
I think I got them all.