GIGABYTE Z370-AORUS GAMING 5 I5-8600K
GIGABTYE GTX 1080 Gaming G1 8GB
Klevv cras II 16GB 3000MHz DDr4 White led
SEASONIC FOCUS PLUS 650W GOLD
CRYORIG H7
TOSHIBA 1TB 7200 RPM
650W is more than sufficient for GTX 1080. It can even support a GTX 1080 Ti.
Maybe you can try these methods and see if it helps:
1). Make sure under your BIOs setting you have set your GPU option to "Auto" which it can auto detect whether it is a IGFX(Internal Graphics) or external/dedicated GPU.
2). Try resetting the CMOS or flashing the BIOs to the latest version just in case it got corrupted.
3). You may have contamination in the PCIe slot. Blow out the slot with compressed air from a canister and clean the terminals with Isopropyl alchohol 95%. Only do this with power turned off and Recheck your connections and that the card is seated properly.
4). Check the card in another system and if it works in that system then there is a problem with your Motherboard.
Hope this helps..

