What is just fine? The video card or the monitor?
I ask because I want to know if the HDMI on the video card works with anything else (TV, another monitor) that has HDMI to determine if the HDMI port on the video card is bad or not. If the HDMI port on the video card works with everything but the HP monitor you have, then the monitor might have a bad port. Or it could be a bad cable.
If the only device you have to plug this PC into is the monitor, and it works with DP, then you're good. If you want to use the HDMI port on the video card for something else, you have to go through some specific troubleshooting to identify the cause of the issue. Right not, we have 3 possibilities, maybe 4.
- The HDMI port on the video card is bad
- The HDMI port on the HP monitor is bad
- The HDMI cable you're trying to use is bad
- *The HDMI port on your motherboard is being used instead of the port on the video card
*this is important. Most, if not all, consumer (non-server grade) motherboards have a minimum of one HDMI port. Some will also have other video ports, but HDMI is "usually" the minimum. You want to make sure you aren't using this port because when an external video card is added (one plugged into a PCIE slot) you would normally disable the on-board video since it is no longer needed. This will make the on-board video ports, HDMI included, useless. So, make sure every cable is plugged into the video card when troubleshooting.