Ran into the same exact problem at my workplace. Two machines both went crazy over sync issues. Moving the card to slot 2 solved it.
We hadn’t updated anything in over a month, so the fact that the cards suddenly (and at the exact same time) both went out on the machines is a little baffling. We’ve had one machine almost a year, and the other for roughly a month, and the problem happened at the same time for both.
The only thing that was done on either machine that seemed related was two days ago I did screen sharing…