You have a mobo that includes its own graphics chip for video output. Plus you have your own graphics card. I presume the graphics card is installed, and you are connecting your monitor to that card's output.
Many mobos like yours arrive with a default setting to output video using the mobo's chip, and that goes out the video connectors on the mobo's BACK PANEL, and NOT from the connectors on your video card.
First, change your connection. Plug your monitor into the video output on the mobo's back panel, then boot the machine. You should see a display that way. If you do, you're ready to use that to change its setup.
Find your mobo's manual, and look through it for two things. The first is how to get into BIOS Setup. Once you get there. Look for where you set how video output is configured. Go there and set it to use the video card you have added into a PCIe slot. After making your change, remember to use the SAVE and EXIT process to save your new setting. The machine will reboot, but you will NOT see anything on your monitor. Now, move the monitor cable back to the output connector on your video card, and you should see the display there now.