Question PC sometimes won't recognize screen & Power button will NOT turn off PC,Whether pressed or held.

Nov 7, 2020
I'm not sure if this is the right section to ask this my apologies if it isn't.

About a month ago I had a Dell XPS 8700 case lying around and not being used because the GPU was dead, so I decided to get a new GPU and PSU and Essentially just gutted the old case and put it in a new one,Adding the new parts.(Gigabyte G1 GTX 1060 6GB in place of AMD r9 270x, Cougar VTE600W bronze in place of generic Dell PSU )

To cut it short, everything is working fine, except that sometimes The PC won't "recognize" that the screen is connected and just run idle, tried replugging the HDMI cable from both sides and turning the screen on/off...nothing, so I try to turn the system off from the power button, nothing, hold it for 2 full minutes..also nothing, I'm only left with Power switch on the PSU itself, and I'm aware that this could cause all kinds of problems, but when it restarts it work just fine.

I've read that the button thing might be a BIOS problem but I'm scared to tinker with that.

Any help with this problem would be really appreciated.

System specs:
CPU: Intel core i7-4770
GPU: Gigabyte G1 1060 6GB
HDD: Toshiba 2TB
Motherboard: Dell XPS 8700 Z87 LGA 1150 Intel motherboard KWVT8