BFG 7800GS OC and MSI 6702E problem, no video signal after post

Question

Okay this problem has me stumped and the techs at BFG are thinking there is a conflict problem with my mobo and this card.
Heres the case:
I got 1 - BFG 7800GS/OC and I installed it in my MSI 6702E (K8T Neo2 F/FIR). The system runs its POST fine and it gets to the OS selection screen. Right after that (where it should load windows) the screen goes black and the screen acts like its looking for a signal on its digital or analog feeds (a small window appears on my screen indicating signal on which port and for me its on the digital).
This is what I've tried so far:
1)  I unistalled NVIDA drivers
2)  Tried booting to safe mode
3)  I bought an Antec SmartPower 2.0 PSU 500W (see http://www.antec.com/us/productDetails.php?ProdID=26500 for specs)
4) repeated steps 1 and 2 with new PSU
5) Updated to 9.3 BIOS
6) Confirmed VIA drivers version is latest (5.10a)
7) Got another BFG7800GS OC and repeated steps 1 and 2
8) Bought another PSU its a BFG 650W (see http://www.bfgtech.com/power_supply_650W.html for specs)
9) repeated steps 1 and 2 with 1st and 2nd 7800GS
I have tested the cards in another AGP system and the cards work perfectly. I've talked to the BFG tech support and they feel their could be a conflict with the mobo, but I'm at a loss to find any info on that in these foums.
Note that both PSUs have 12v rails that are rated combined >20 Amps
My system Specs:
Athalong 64 3200+
K8T Neo2 F/FIR
2 - 512 MB Kingston DDR 400
2 - 256 MB DDR 400
1 - Seagate 200GB HDD
1 - WD 80 GB HDD
1 - TDK DVD +/- RW
SB Audigy 2 ZS Gamer
PNY 6800 - soft modded to GT with extra Vertex Shader enbled

Answer 1

I can't boot into safe mode, normal mode, vga mode. The computer only POSTs and then gives me the OS selection, which I then choose and thats it.... black screen. No sound, no video then eventually my screen goes into power saving mode. I don't even get the windows logo screen.
My previous system worked great minus the declineing game performances. I'm simply replacing the softmodded PNY 6800 to this new BFG 7800 GS. I know the video card working is not the issue since I had it working perfectly in another PC. So no this is not a new build.
Yeah so the deal on those 2- 256 MB DDR 400 ram sticks is that there is no visable brand name. There is a sticker on it indicating its stats and a little logo of some company I don't recognize. The RAM sticks themselves have a silver colored heat spreader, but I don't think that has anything to do with the situation. The RAM in this computer is top notch and its been stable for over a year.
I'm really at a loss here on what the problem might be, but I have to imagine there is some issue going on with the AGP bus. I've tried messing with the BIOS settings and setting fast writes to off, AGP to 4x, aperature to 256 mb then back down to 32 mb. All those settings result in the same symptoms.
Man this is really perplexing since it seems others have this same board wih this card running fine. Since I can't seem to find anyone with a similar issue.