The PC starts but does not display an image on the screen. What is the problem?

Question

Computers

I welcome everyone.

The situation is the following. By negligence, I turned off the power of the PC, after restarting, the image on the screen ceased to be displayed. I connected another video card to the PC, everything worked.

After that, I connected the old video card, which was at the time of the breakdown. The image also began to be displayed from it, however, at the same time, the splash screen of the motherboard is not displayed, and if I press the key combination to call the BIOS, a black screen appears.

If I turn it on and wait for about 15 seconds (all this time a black screen) - the OS starts, moreover, without the motherboard splash screen. If I reset the BIOS, the PC from this video card again does not display the image on the screen until I put another video card. After that, the old one starts working.

I connected the monitor with the same cable to another PC - everything works as it should. If I connect TWO monitors to my video card, then everything starts normally. However, the splash mat. The board is always displayed on another monitor (not on the one from which I am sitting, but on the second one).

I would be grateful for good advice.
Thank you. All the best.