This has already been narrowed down I believe to an ATI Catalyst Driver issue but so far I've had no luck with driver upgrades/updates, or the FAQ's at ATI tech support. I did get the DVI working again but as soon as I installed the (off the disk) ATI drivers, same problem returns. Here is what I'm dealing with.
ATTEMPTING DVI-only(no D-sub connected) boot up:
Boots ok.
Posts ok. (with DVI video)
Begins loading Windows OK (DVI video).
20 seconds or so in, video out, black, monitor reports no signal and a few seconds later falls into stand-by mode.
If at this point if you connect a D-SUB cable (w/o restarting the machine, as is) there is windows ok, it continued booting in the darkenss. D-SUB ok, DVI out. below are some further detalils.
SCEPTRE X20WG-NAGA, AMD X2 4000+ over-clocked to 2.25 (from 2.10)
Video is ATI ALLINONDER 2006 PCI-E edition, latest Catalyst drivers. (right now I'm back on the as-shipped-w/disk-drivers but I've tried both)
Monitor using latest Sceptre driver.
I've tried H/W accellertation set to NONE, very low resolutions, 16bit color... my monitor does auto detect input but also has a button on the front to manually select. If you try that it either stays black or pops back on as D-SUB (if connected) ATI spoke of a "USB conflict". So I disabled all USB in the BIOS. That looked like it was working untill I reinstalled the ATI drivers, and then , DVI out again.