PC won't boot, no beeps or display

Pjt890

Honorable
Sep 18, 2013
4
0
10,510
Had the PC for about 2 years, turned itself off today. When switched on no beep comes from the internal speaker and the system doesn't boot (no motherboard screen). Monitor definitely works. Tried removing all expansion cards and resetting CMOS. Assuming it's either the motherboard or the PSU? Please help.