DVI connection stopped working for higher video resolutions

I've been using the same Nvidia 6800GS card and Dell 2001FP monitor for about a year now, always with Nvidia's official drivers. A couple of weeks ago I noticed my monitor wasn't coming out of standby properly. The power light and backlight would come on, suggesting there was a signal, but the picture remained black. After trying different driver versions and X settings, I noticed yesterday that resolutions of 1024x768 and lower work just fine.

A little Googling pointed to the DVI connection as a likely culprit, so now I'm using the VGA connector instead, and have no problems getting the monitor's native 1600x1200 resolution that way. I'm just a little bothered that the DVI stopped working, and the VGA connection isn't quite as sharp.

I recall back when I had an ATI card and ran Windows that ATI had a driver option to use lower DVI frequencies for large monitors, and that solved similar issues for me at the time. Unfortunately, I don't see anything similar in Appendix B of Nvidia's README (X Configuration Settings). Does anyone know of a fix for the DVI frequency?

I'm using Debian Testing with Xorg 7.2 and Nvidia's 100.14.11 driver, by the way.

For posterity, when seems to have worked in my case was to physically isolate the DVI cable as much as possible from other cables. I suspect a power cable or power supply was creating interference in the DVI.