Are you sure your DVI cable works?

Just for the sake of trying have you tried a DVI to vga adapter to see if there's any output from the port?

The DVI port is DVI-D, so a DVI to VGA adapter won't work. The DVI cable works with other video cards just fine.

I have an Elsa GF256 SDR with the same SI DVI chip that won't output DVI either.
It has one or more cracked solder joints underneath the GPU from overheating after fan failure causing random VRAM errors so I always thought this was the issue.
Maybe DVI has to be enabled in video BIOS or driver first?
Maybe the card's video BIOS has been flashed and the new BIOS does not support DVI?

Following this thread with great interest!

It has been documented in other threads that the DVI standard was pretty much new tech and Nvidia didn't do a good job making it impossible for some monitors to get a picture. Same persists with the DVI on the GF2.

What happens when you get to Windows? Does it work then? (I.e., is it only black while posting and booting?) I have an ATI Radeon 8500 that does the same thing. Early DVI, 1080p/4K monitors, HDMI switching and matrix in between... it can't hang. Someone here told me it has to do with the card and EDID setting up an incompatible mode until the driver loads and does something more sensible. (Here it is: Re: Radeon & DVI switching)

I got a second CT6960 with DVI port that did the same thing and finally got around to playing with this some more as a result. As SirNickity suggested, the DVI port works fine in Windows. I booted to Windows XP and installed the official nVidia drivers (45.23). The nvidia driver controls have an option to toggle between analog and digital display output. Once I switched to digital, I got output on the DVI port! It still doesn't display anything during POST or the XP boot screen, but it works once you get to the XP Welcome screen. This must have been really annoying in the era of LCD monitors that only had a DVI port.

Did you test this with your first card?

Isn't there an Nvidia video BIOS options that controls whether video is mirrored on both ports on boot ?

I tested it with both cards and it worked the same way.

Good so at least you know both cards are working properly and now you have a spare

According to this ftp://ftp.iks-jena.de/mitarb/lutz/unix/asus-v … ia/BkNVBIOS.pdf
BIOS versions prior to 2.10.04.02.00 do not initialize the DVI TMDS at boot .
"Add code during bootup to initialize SI 154/164 via I2C port when booting
to DFP."

So now I need to work on updating the BIOS.