GA-Z77-DS3H motherboard, rev 1.0, BIOS F9
BeQuiet 430W PSU
i5 3570K CPU, no overclocking
8GB of Corsair Vengeance RAM running at XMP
Onboard HD4000 graphics through DVI
All headers disconnected from the motherboard
The original problem was in setting up a hackintosh, but bear with me, I don't think this is a sw problem. If I had any more than one hard drive, then:
Power on and boot, then sleep and wake, then restart, get a failure to POST. HD cycles repeatedly, no beeps, no screen. Reset button does not help, I need to power off. The same thing happens if I use the reset switch rather than restart.
I managed to replicate the problem through slight electrical abuse - not really sure if this proves anything or not.
Power on, wait for the beep, power off, power on as soon as possible. Fails to POST, regardless of what drives there are in the system - even true with no drives.
If I wait 5 seconds between power off and power on, it boots just fine.
I originally had the BIOS set to optimized defaults plus SATA in AHCI mode. Since then I've mucked around with setting voltages to Normal rather than Auto, RAM at XMP and at Normal, swapping drives to different SATA ports, disconnecting all the case connectors from USB headers and the like, none of which makes a jot of difference.
I'm borrowing a different PSU to try this evening - but the BeQuiet 430 is not a cheap PSU. It's made in Germany, and is an 80+ PSU. I just looked up the XFX450 and it costs less. I realise price isn't necessarily an indication of quality, but it's not a bad place to start!
The power usage of the system (just measured with a plugin power meter) at startup or when it's benchmarking is <100W.