Computer shuts off randomly after use. Must flip PSU switch for it to come back on.

Heislegend

Distinguished
Jan 11, 2014
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New build for a friend, so the parts have no use and are dust free. Like I mentioned, pc works for about an hour then the system shuts off. PSU switch must be flipped to turn back on. He says it's randomly and not just when under load. CPU and GPU temps seem to be fine. Is the PSU just a dud or is there anything else that could be causing this?

CPU: AMD FX-6300 3.5GHz 6-Core Processor
Motherboard: Asus M5A97 R2.0 ATX AM3+ Motherboard
Memory: A-Data XPG Gaming Series 8GB (1 x 8GB) DDR3-1600 Memory
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive
Video Card: Gigabyte Radeon R9 270 2GB Video Card
Case: Rosewill CHALLENGER ATX Mid Tower Case
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply