I have installed the GTX 970 SSC in my Optiplex 980. Connected DVI cable from monitor to DVI-D port on new graphics card. Started computer and the Windows 10 logo comes up on monitor & the "spinning wheel" appears below the logo indicating the boot is in process. Pretty quickly, the "spinning wheel" on the monitor freezes and the fans on the GTX 970 stop spinning. Cycled power multiple times with same result each time. Any ideas on what I'm doing wrong would be appreciated.