I have a Z77X-UD3H Rev 1.0. Generally very stable; I can leave PC running for days without any issues.
However, the majority of the times when I shut the PC down, whether this be a Windows shut down, hibernate or sleep, I cannot resume/power the PC back up.
Sometimes I press the power-on button, and nothing happens for 5-10 seconds, but then the machine starts to boot up, and works fine.
If I had put the PC to sleep or hibernated, I usually press the left mouse button to wake it up. The light on the mouse indicates it has power, but it doesn't wake. This is hit-and miss (sometimes does, sometime doesn't).
Sometimes the PC doesn't power back up at all. I have to hold the power button in for 20 secs, then the mobo detects the BIOS is corrupt and copies from the backup.
I have tried switching to the backup BIOS via the mobo physical switch, but the same thing happens.
I tried updating the BIOS to the latest version, but didn't seem to make much difference, and I lose the BIOS upgrade when it says it is corrupt and copies from backup (I suppose I could flash it to both main and backup BIOSes).
Any ideas what the problem could be?