"new" PC won't start with gfx card installed

I put the guts (motherboard, processor, ram)from a Dell optiplex 7010 into my old case. The transplant worked and this machine runs fine until I install my zotac gtx 1060 3gb. With the old motherboard (gigabyte ga-z68xp-ud3) and the same power supply (antech 550w) it ran fine. This machine runs fine until I give it the video card. Could the card have failed? I was able to start with the onboard graphics and install the nvidia software. Also updated the BIOS on the motherboard, disabled SERR messages, set graphics adapter selection to auto and I'm just stuck for ideas. Thank you.