Question PC wont boot with Displayport connected

[KKun]

When I try to turn on my pc with the display plugged in via DP (and one via HDMI) it wont boot, but if I do it with both HDMI it will (and the monitor works perfectly). I tried a DP cable from my friend but it still wouldn't work. When I start my pc via HDMI and then plug in the DP I can hear the sound that something connected but I still can't see anything, but atleast the pc is still turned on. I tried to update the drivers etc. but it still doesnt work. I can see in the NVIDIA settings that the display is connected but I cant "activate" it via the app.

 

[rgd1101]

full system spec? include brand and model of the psu

 

[KKun]

full system spec? include brand and model of the psu

gigabyte z390 gaming x
i7-9700k
RTX 3060 Ti
16gb RAM
Thermaltake TR2 S - 750W

The DP I use is a 20-pin. I heard that those arent the best.