DVI-D cables & ATI cards

[Thermal]

I have two PC's, one has a 9800Se and the other a X600XT. The monitors are a Viewsonic VX900 & a Philips 190P6. The monitors work with the supplied single-link DVI-D cables but not with a Belkin DVI-D dual-link cable. There is a subtle difference between the cables in that the dual-link has three of the pins connect to plug flange. The display is jumbled and was wondering if it was because the video card is confusing the monitor into analog mode. There are threads about problems with digital displays and ATI cards but none mention differences between dual and single link.