Sounds like Asus mobo White VGA error on boot. Try temporarily putting the gpu in a lower slot and rebooting as that uses the chipset pcie lanes, not cpu pcie lanes, and allows the bios to recognise the gpu.
Also can try using hdmi cord to monitor instead of display port until after a successful boot, often times dp has issues on original startup since drivers are not loaded and it'll fail on the pin #20 handshake.