rx 570 turning on but not being detected by bios and device manager

[Abdkidlikbuk]

Hi, I just built my first pc and it took some time for the parts to arrive. The GPU (MSI RX 570 Gaming X 4G) was the last part and by then I had already setup my pc. I put my RX 570 in with the 8 pin connector and tried to boot up my pc. The first thing I noticed is that the gpu turned on, but no display or anything came up. So I switched back to my MB's VGA Port and installed the drivers thinking that that was the problem. Rebooted my pc but it still didn't come up. So I went to device manager and I realized that the gpu isn't even listed there. Also not listed in BIOS. What could be the problem? Also I don't have a spare pc to test this GPU in :((((((( Here are some things I have done: Flashed BIOS, Reinstalled Windows, and DDU'd all my integrated graphics drivers.
Specs:

CPU:G3258 @ 3.2 Ghz (terrible bottleneck sadly, will upgrade soon tho)

Motherboard: Gigabyte GA-H81M-ds2 rev 3.0

Ram: Single stick 8gb ddr3

PSU: Some branded one I took out from a HP pavilion. it says 385W max. (It says delta electronics so I am guessing that is the brand)

GPU: RX 570 Gaming X 4G MSI

Note: I am currently using a 6 pin to 8 pin adapter because the psu doesn't have an 8 pin connector only has a 6 pin.

Feel free to ask for details as I am always online! ( ͡° ͜ʖ ͡°)