I vaguely remember ~7 years ago when I built it having issues with the gpus. The main issue was that I needed to boot my OS with a single card, get everything up and running, then shut down again and add the SLI and 2nd card. I also vaguely remember thinking the wiring was silly but it worked and for 7 years it was “if it ain’t broke don’t fix it” until now.
Update on my building journey: my wife’s new build (waiting for 3 more case fans):
Yeah my sli was useless about 4 years ago when games stopped supporting it. That’s why I’m giving her my 2nd card because it’s useless in my rig.
As for a new build for me, I should probably just wholesale and upgrade to a DDR5/current chip mobo because I think my i7 6700 is really what’s holding me back past my card.