Question PC won’t boot without video connected.

[240hz]

Basically the title of this thread. It did use to work and boot without video plugged in. But now it no longer does. Just out of nowhere. I was connecting some new fans and when I went to try them without any cables connected to the PC but the power cable, it didn’t boot. I connected the video cable to see if anything was showing up and it booted to desktop all fine. It makes no sense. All I want is for this problem to be on the motherboard, because I was thinking of changing it before this, anyways. I don’t think it’s the GPU, since I removed it and tried again with the motherboard video ports and same story. Could it be the CPU or RAM?? By the way I know it doesn’t boot because I have an MSI mobo (ez debug led thing) and also because I connected video AFTER it failed to boot and it seemed to be a frozen screen of the black screen with white console letters before the OS even starts... Oh and also because I didn’t see iCue with my lighting profile.

 

[240hz]

Just found out that according to the Ez debug led, my GPU was not detected or it failed. Still happens with GPU out of the system.
Also specs:
CPU: i7-7700k
GPU: Asus Strix GTX 1070
Motherboard: msi z270 gaming plus
RAM: corsair vengeance 8gbx2 2333mhz
And an M2 (crucial 256gb)
*4 fans installed, including the cpu fan. one of them is DC.
***I also just remembered that all of this started happening after I tried plugging in a fifth fan (DC) to the sys-fan connector closest to the middle of the board. It could be coincidence or maybe it made this happen.