skeeder, I agree with you on the supposedly highest dvi res at 1600x1200. If it wasn't for our almighty PS I would have wrote the same thing as you(I have before).
I'll just say that all the cards I've used DVI with, bar my X1900, have said the max DVI res supported it 1600x1200. All have been perfectly happy at 1680x1050 and 1920x1200.
For the record, thats:
FireGL 8800
Radeon 9000
Radeon 9500 Pro
GeForce 5900XT
GeForce 6800GT
GeForce 6800GS
The X1900 is a dual DVI card, so supports up to 2560x1600 officially.
He has an FX series card so it is possible he can get 1680x1050 like PS. Interesting to find out.
EDIT: Read this on the forum
On my old MSI 5600xt graphics card, the display works on the DVI cable only up to 1280x1024.
It doesn't confirm anything, just wanted to share that it is a difference between the cards. Some might work and some might not.