nVidia & OptiPlex 7050 MT

Our company has purchased a small quantity of 7050 MTs, and we are replacing the stock AMD Radeon R5 430 with an nVidia GT 430.  It works, but wit one odd issue - namely, I don't get any video until after Windows has started loading.  I can actually hook up a monitor to the HDMI port on the motherboard and it works simultaneously with the nVidia card.

This is...not behavior I am used to seeing.  And it's not consistent with the behavior I was seeing with the AMD card installed (and, before you ask, we have reasons for using nVidia cards so just sticking with the AMD or onboard video isn't really an option).  It's not stopping us from doing anything, and as long as I know that if I ever want to get to the BIOS i just have to move one of the screens to the onboard video I can deal with it.

But it's decidedly odd behavior, and I'm curious as to whether I can do anything about it going forward.