Troubleshooting correctable garbled video

Hello,

I have an NVidia Gforce 8500 GT connected to a 42" TV, and I often get garbled video whenever the resolution is reset or the machine is rebooted or there is some sort of display reset. This is consistently corrected by unplugging and reconnecting the DVI cable (although this sometimes takes multiple tries), or simply toggling between video inputs on the TV. This isn't an NVidia driver issue, because this often happens right at boot time before the OS is even loaded.

What sorts of issues contribute to these sorts of problems, and what sorts of things can I try? I've tried multiple DVI cables, which seem to produce this problem at different frequencies. Any suggestions?

That's interesting, how did you figure that out, just so that I understand? Would using an HDMI cable produce better results w/o the video card upgrade?