I don't think there are very many original IBM PCs that still work.
(Please provide your complete system specs, including brand and model (not just wattage) of your PSU if you would like more relevant responses. Thanks)
I have and AMD fx 4130 quad core processor, 8gb ddr3 ram, nvidia gtx 750 2gb gdrr5, 850w 16w 42A, Asus M5A78L-M/USB3 Motherboard (Socket AM3+, Up to 16GB DDR3, USB 3.0, uATX)
Could really be anything. More into specifics if possible so that people are much more able to assist you. Like, what are you in the process of doing when it reboots, who makes your psu and what model, because some manufactures put out pieces of crap they call psu's. The more specific you are the better