EDIT2: Always forget that SLI is disabled when you install new drivers, since it makes no sense at all. Re-enabled it and I'm seeing ~30 frames higher (from average 45 over all to average 77 over all) so not good scaling, but not terrible. Going to re-enable DX12 and see if it's any different or if it's true as another poster here said and SLI isn't available yet.
Holy shit. I forgot about this as well. Wondering why the game ran like absolute ass at places. Just turned settings down till it was playable again. Just checked, and SLI was off. Why the hell NVidea thinks that is a good idea, i'll never know. If it's selected on before the upgrade, leave it the fuck on! Jesus.