Question : Problem: DVI works on one monitor but not the other.... PLEAS HELP NEED GOOD TECH!

This is the damnedest thing I have ever seen....

SYSTEM:
MSI P6N Diamond
Intel Core 2 Duo, 3.0Ghz
3GB of the Balistix high speed ram.
2x XFX nVIDIA Gforce 8600 GTS SLI
ULTRA 600w PSU
2 x WD 74GB WD Raptor Drives  (Raid stripe)
2 x WD 500GB WD  Drives (Raid Span)
NEC AccuSync aslcd223wxm-bk 22 Monitor

When I built this system, I could NOT GET any of my DVI to VGA adapters to work.  Each card came with 2.   The NEC monitor worked on the old computer, using VGA ables.  Because we could not get dvi to vga to work, we hooked up the DVI port to a DVI cable on the NC and to the TOP video card.  NOTHING.  It would not show DVI port at all, only VGA.   Could not selct or change to a DVI Port.    

I hooked up my DELL, and it worked just fine.  We called NEC and they sent a new replacement monitor.  When we hooked this one up, right a way it said DVI and showed the DVI icon on the monitor, but the power light went form green to amber and said no signal.  It was not detecting any DVI signal.

I hooked up my Dell monitor, and once again it seemed fine.   So I am thinking they sent me a bad replacment..  BUT,  One time, when my dell was plugged in, WHILE POWER WAS ON... I unpluged it.. and plugged the NEC in... AND POOF we had a pic.  All was fine until I rebooted that pc then  NO SIGNAL.

I guess I want to know is there something on the SLI cards I could be over looking?  Why did it work that one time?

I thought that perhaps the dvi cable I was using was bad,  so I used my cable form my pc and my dell display, and tried it on the other NC and system and still no signal.

WHY WONT the vga to DVI adapter work?  This is what has me wondering.

I had to hook up my DELL monitor with DVI cable direct.  It worked just fine.

Answer : Problem: DVI works on one monitor but not the other.... PLEAS HELP NEED GOOD TECH!

Just want to be sure...but does the NEC support the resolution and refresh rate you are trying to run?