If no screen, you check if you have plug in the extra 2 molex and 1 sata needed to power the board.

In picture, i dont see plug in the pcie_pwr1 molex cable yet. check pcie_pwr2 and sata_pow1.

disconnect the pcie riser and gpu.

start up and see if boot screen appear and press F2

there is setting use onboard graphic, pcie or both.

You must set both when there are riser gpu in use.

make clean install Windows 10 1703

Its windows 10 problem.

Windows 10 Pro
1703 running fine
upgraded to 1709 running fine
1709 upgrade 1803 random freezing, start menu not working, etc

Then done:-
clean install 1803 random freezing, start menu not working, etc
clean install 1709 random freezing, start menu not working, etc
clean install 1703 running fine again