That biz with the PSUs is bizarre.. what brand of motherboard was the original (failing) one again -- ASRock ?

For DVI-D out from the ASUS mobo -- if the new mobo has integrated Intel video, then one can get/use a tiny little PCIe card that has a single onboard chip and a DVI-D output. Uses practically no power -- just provides a DVI-D connector for the integrated Intel video.

But it does take up a PCIe slot.

EDIT: the search terms for this kind of adapter are ADD2 and SVDO.

Cheers