4 days in, screen goes black trying to install

After numerous issues with High Sierra I've reformatted my SSD and am going back to Sierra. I have two USB sticks, one with Sierra and one with High Sierra. The new issue is that I get to the apple loading screen (before the install) and about 75% in the screen turns off. I've removed lilu and nvidia kexts, removed the GPU itself and have the Display Port cable connected directly the mobo. In the BIOS I have use internal graphics turned on. In clover I have inject Intel Graphics checked. The HDMI port doesn't seem to put out a signal at all. I need help. I am 4 long days into this thing and it seems like I'm going backwards. Gigabyte z170x gaming 5 and evga gtx 960