Unfortunately, the mainboard does not work for me. The display is always black. The LED on the board says that the graphics card is not recognised, but it is running on the other computer. I then tested the HDMI port on the mainboard, but that connection doesn't work either. It should work like this, shouldn't it? I checked the cable. Both ATX connectors are plugged in. Does anyone have any idea what the problem could be? Is the card defective? Can I exchange it?