That makes a
lot of sense. There's also
dual-DVI vs Single-DVI, and sorry I didn't see earlier your supposition, as this might or might not cause you issues. Either 1920x1080 is the highest for single-link, or just outside the spec. Hopefully, either you got dual link, or it's in the single link area. I had to troubleshoot that issue for a couple of days before realizing it, so I wanted to throw that out there just in case you have that problem.
(And funny, it's the machine that I was saying I could do that resolution with that I had that problem on! It seems like I would have remembered that frustration... sorry again.)