Question about ASUS GeForce GTX 1080 STRIX A8G GAMING

So far it looks like this: I have three monitors on the table. All three are connected. Two via HDMI and one via DVI. The DVI works and so does one HDMI, only the one HDMI output on the graphics card doesn't work, no matter how I reconnect it. Because when I change the connection, one of them doesn't work again. In the display settings, I have already clicked on the option "Extend this display". Is it possible that the HDMI output is broken or what could be the cause?

I have tried again. Nothing comes out of one connection. If I plug the cables in the other way round, one monitor works but not the other. Is the connection broken or do I have to do something else?