Windows won't boot after adding second graphics card or enabling iGPU

Question

Here is my system info:

Windows 10 pro 64 - ver 1809 - build 17763.195

i7-8700

Asus Prime Z390-A motherboard

64GB (4x16) Ripjaws V series DDR4 2666 CL15

2 x ADATA XPG SX6000Pro 512GB PCIe Gen 3x4 M.2 2280 NVMe drives (RAID 1)

PNY Quadro P2000 graphics card

PNY Quadro P400 graphics card

(all drivers and BIOS are up to date and installed)

If I only have one GC installed (either one, it doesn't matter) in either the x16_1 or x16_2 slot on the motherboard the system boots fine and sees the card and my monitors. If I add a second card, the system will try to boot. I get the spinning dots, but they stall out (two to three times) and then I get a blue screen that says that I don't have a bootable device. If I power off then power back on and inter the BIOS, my drives do not show up. If I then power off again, remove one GC, and restart, the system boots fine.

I have also tried to just enable the iGPU along with a single GC and the same thing happens.

I have worked with Asus, PNY and Nvidia and everyone says that their hardware is good. So, I'm down to a possible windows problem.

Is there something I need to do to make two GC's work in Win 10?

Answer 1

Looks like the ASUS board is just poorly engineered. Switched to GIGABYTE board and it works.