Specs:
Mobo: Z77X-UD5H rev 1.0 with F15q BIOS
CPU: Intel i5 2500k
GPU: Nvidia GTX 480
RAM: corsair vengeance 16Gb
PSU: 680 Watts
The issue: sometimes, when I wake from sleep, the system tries to wake, but ends up rebooting a couple times until I either disconnect power from the entire rig, or wait for a "boot error" message from the BIOS. The problem seems to correlate with the time I leave the system in sleep: for example, I can put the system to sleep and wake it without issue if I wake immediately after I put it to sleep, but if I leave it overnight it may have trouble waking.
I've been having this issue for a while now, with all BIOS versions, stock CPU clock speed or overclocked, various BIOS settings, etc. I'm running Windows 8, and this problem did not occur on Windows 7 when I had it installed previously.
I will be happy to answer anyone's questions. Thanks in advance.