No boot when second monitor attached

micromashor · March 9, 2021

System info:

CPU: Ryzen 7 2700x @ 3.7 GHz

MOBO: MSI B450 Tomahawk Max

RAM: 4x8 Corsair Vengeance DDR4 3200 MHz (running at default 2133 MHz for troubleshooting)

GPU: GTX 650

PSU: EVGA 750W 80+ Gold

SSD 1: Crucial P2 1TB NVMe SSD

SSD 2: Samsung 870 QVO 1TB SATA SSD

2 HDDs sitting in the drive stack but disconnected.

Windows 10 Home Version 10.0.18363 Build 18363

BIOS Version 3.30

I recently got a new NVMe SSD (SSD 1 in the above list) and two more sticks of RAM (identical to what I had before) to upgrade from 16 to 32 GB. The RAM install went flawlessly. However, when I tried to boot, all I got was a boot error LED on the motherboard and my main monitor started flashing black, white, red, green, blue, red, green, blue, repeat. No POST with this configuration, so after some fiddling, I figured out that I can only get it to boot if I disconnect my main monitor before booting, then reconnect it after the PC is fully booted. I'm in the process of changing my boot drive from the old SATA SSD (SSD 2) to the new NVMe SSD (SSD 1). I used Macrium Reflect to clone the old drive to the new one, and I'm able to boot to either of them just by choosing in the boot menu, but only while the main monitor is disconnected. Why is this? Thanks in advance.