The problem with the Display Port of the video card

The problem is of the following nature, when the PC starts connected to the monitor via the Display Port, the system does not boot (I have a percentage without integrated graphics, so it would be loaded on the inline). The computer itself is buzzing, the ventilators are working but there is no signal to the monitor. When connected via HDMI, everything loads without problems, it could be attributed to the inoperative Display Port output, but with Windows loaded, if you unplug HDMI and cut off the Display Port cable, select DP in the monica settings as a signal source, then voila! Everything works through DP, but this is already when the system is running. Why is it not loaded via DP from the start? Initially, at the start, DP was selected as a source, do not write that you forgot to switch from HDMI. System - Win10. And could there be a problem with SLI?
Perhaps the problem is in the priority of the image output port from the video card, but where to configure it?