I have a EVGA 650. my graphic card is light up so i thinks its power up. I didn't see my card on the bios but i'm not shure where to look? when I check my peripheral in graphic card I see intel HD graphic 530. I'm using an HDMI slot on my motherboard right now and my monitor is working fine.
sorry but I'm not shure what you mean by onboard video (english is not my mother tongue)
Getting enough power to get lights does not mean the card is good or it's getting enough power. It takes only a few watts to light up an LED strip. When you plug in the 970, you are moving the video cord to the card right? Do you see the BIOS screen when you start the computer then or is it blank the whole time? Did you try a different port in the card?