That date should make the EFI version 1003 which should definitely support the 8120, I ran my 8150 on that version for a while.
What I'd recommend:
1. Power off completely remove 120V cable to PSU
2. Check a few things:
Video Card: Seated properly, PCI-E power connecters connected to video card3. Install only 1 memory module into DIMM A1 (left most closest to CPU)
Power supply: CPU4+4 connected to only the EATX12V located to the upper left of the MB
Thermal: Proper contact with CPU cooler, Thermal compound properly applied, fan plugged into CPU_FAN.
4. Clear RTC RAM (see 2-18 in manual)
5. Try and boot to EFI
I know I had one hell of a hard time booting the first time and all these things above helped me out.