I just completed my PC build: i3-6100 CPU msi b150 gaming motherboard XFX Radeon RX480 8Gb Corsair CX 450M PSU
So I installed the GPU on the first slot, the x16. It didn't work. I get no picture, but when I plug my cable in the integrated graphics, there is picture. The GPU lights up and the fans start spinning, so it's getting power. Then I tried putting it in the other slot, the x4 one. It works normaly, it gets detected and I can use it that way.
Why is that happening?