I've tried several power supplies however I'm still getting the error led. When the CPU cable is plugged in the computer shuts down immediately (fans and stuff get power briefly) after it is powered on, however, when it is unplugged it seems to start normally except for an expected post code 'C'. I've swapped out the power supply for one working in a nearly identical computer and there seem to be no changes (both PSUs are work with the other system). Any suggestions? Thanks in advance.