Ensure the24-pin ATX and8/4-pin CPU power connectors are firmly plugged into the motherboard. If your CPU has onboard video, remove the discrete GPU and display from the motherboard's video outputs to rule out GPU issues.
ASUS PRIME B360M-C/CSM LGA1151 DDR4 Intel B360 Chipset mATX Motherboard w/ IO
ASUS PRIME Z270-A LGA1151 Intel Motherboard w/ IO Shield | Fast Ship, US Seller!
ASUS PRIME B250M-C mATX Motherboard LGA1151 6TH/7TH GEN CPU DDR4 w/IO- Tested
Asus Prime Z370-A LGA1151 DDR4 Motherboard with I/O Shield
ASUS PRIME Z390-P Intel Z390 LGA1151 ATX 8GB DDR4 Intel Celeron CPU
ASUS PRIME Z390-P Intel Z390 LGA1151 ATX DDR4 4266MHz Dual M.2 HDMI USB3.1 Gen2