650w sivlerstone from my old pc
That was the first thing that caught my eye.
If you happen to have another PSU lying around, try that one.
Also, just to make sure I understood correctly: While in BIOS, everything works but when you let it boot, it restarts?
When exactly does it restart? Before or while it tries to load the OS?
Can you boot from another bootable device? (bootable USB stick, boot CD/DVD etc.)