Problem with new rig, plz assist.

Hello,
I recently (read: Dec 31, 2008) purchased a new rig, which I assembled myself (like I always do).
Specs follow:
CPU: Phenom II X4 920
M/B: ASUS M3A79-T Deluxe
RAM: 16 GB OCZ (4 sticks, 4 GB each), stick model number OCZ2VU8008GK, PC2-6400 800MHz
Gfx card: ASUS ENGTX 260/HTDP/896M/A (gpu is nvidia GTX 260 with 896 MB GDDR3)
HDDs: 2x WD Caviar black 500 GB SATA II (model number WD5001AALS)
PSU: Enermax Liberty 620W (model ELT620AWT) (NOT the Liberty Eco series, the slightly older plain Liberty ones)
(ratings: +3.3V 28A, +5V 32 A [170W combined 3.3V and 5V], +12V1 22A, +12V2 22A [36A combined 2V rails], -12V
0.6A, +5Vsb 3A)

Problem: System powers up, all fans operate, HDDs and ODD spin up, no beep, no monitor signal (monitor stays on standby).
Attempts thus far:
assembled bare system (M/B, CPU, PSU, no RAM or anything else) on non-conductive surface: no change
tried different RAM and Gfx card, proven to work (removed from another system): no change
tried different PSU (CollerMaster 500 W), again working (removed from the same system as RAM and Gfx card): no change

so I'm left with very few possible candidates: M/B or CPU. I would like to hear your opinions, if you have something to add.

There is another detail: the ASUS site states my mobo supports the CPU since BIOS revision 0602, dated Nov 12, 2008.
I have no idea how old my MB is, in terms of BIOS, I purchased it 3 days ago, but could it be having a BIOS nearly 2 months old? and could it be the cause of the problem? Usually an incompatible CPU causes the MB not to start, or to at least beep, this one does nothing.
Until I can eliminate this possibility (which I can't on my own, since I have no AM2 CPU available that works with the MB out of the box) I would like to hear your thoughts as well.