.

[tidy]

.

 

[eton975]

CMOS reset fixed bad settings?

Some weird power supply/mobo capacitor issue? Is the PSU certified as being Haswell ready (PSU IS haswell ready) Were the C6/C7 sleep modes enabled?

 

[tidy]

.

 

[eton975]

What kind of "bad settings" arise spontaneously between reboots (I never touched the BIOS) and cripple the board to the point where it can't even operate it's standby power LED.

My other thought is that the button-cell battery on the mobo has a low voltage, but it's a new mobo. Maybe it was kept in cold storage for a long time?

 

[PhIlLy ChEeSe]

@OP,
You never mentioned the make or model of the power supply?

 

[tidy]

.