Ok,
Well a sign that everything is working ok is a single short beep when the system posts, powers up.
This is the problem, you have a graphics card in the pci-e slot.
But due to the settings of the bios the main display output is switching to the on board graphics port of the board.
That is why you don`t or should not see a post screen, or a bios screen when the key to enter it is pressed.
You should on the first run connect the monitor signal cable to the motherboard.
You should see a post, and be able to see the bios screen when the key is pressed to enter it.
Once in the bios Pci-e or Peg must be set first in the order of graphics ports or interface type to use.
Save the settings before exiting the bios, reconnect the monitor cable to the Pci-e graphics card.
And next time you boot or power up the system the display should work fine.
Why it goes blank is its switching to the on board graphics port of the motherboard to display post and bios. As by default in the bios it is set to initialize it first.
And why you need to change the order to Pci-e.