The Keyboard Controller (KBC) manages the power-on sequence. On the LA-E791P, the KBC communicates with the BIOS via the SPI bus. If you have a "BIOS Corrupt" symptom, the schematic will show you exactly which pins to probe for CS (Chip Select) and Clock signals. D. CPU Core Power (VCore)
Check if the KBC is sending the PM_SLP_S3# signal to wake the chipset.
A resistor or capacitor labeled R102 in Rev 1.0 might have a different value or be removed entirely in Rev 2.0.