Craig wroteThen it's either what Sean suggested, or the fact that your PSU had died. If you still can't get anything working, contact RMA the PSU. Would be handy if you had another one to try? Maybe you do?
Tried a new cable, but PC still wont turn on. I've taken everything out except the cpu and cooler. I'm gonna unplug everything from the psu and try again. I don't have a spare psu which sucks. I can order one I guess. You think it's more likely to be the PSU than motherboard?
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Usually yes. A motherboard like that should have an error code come up when the board is experiencing faults. I would contact the manufacture about a RMA. Maybe the re-seller could help, depends how old the unit is.