I am guessing you have your monitor hooked to the graphics card. Try booting with the monitor connected to the board. If the computer posts, there could be a problem with the card or the pcie slot. if you get post, try the card in a different pcie slot. If you have a card you know works, you can try it in the slot the 1070 is in. if the computer still doesn't post, or still only posts on the board outputs, try resetting the bios.