Area-51 R?, U2719D interferes with UEFI Windows boot

I have a weird problem with a Dell U2719D IPS Monitor. I recently installed this monitor as the main screen in a 3 screen array. It is set for 2560x1440 resolution, while the other two are set at their recommended 1920x1080. I have an Alienware Area-51 with a NVIDIA 1080 GPU, running Windows 10/Pro. Everything runs great, except that I cannot boot to UEFI setup. If I try, I get black screens. If I set one of the low resolution monitors as the main screen, and disconnect the Dell IPS, then I can boot to Set-Up and see the UEFI configuration. This means I cannot run the Repair mode, or change any boot configuration without disconnecting the IPS monitor. Any Ideas, anybody?