My advice would be to not upgrade the motherboard.
I don't see what advantages it has to you. You can't overclock the CPU because it's not a -K model. Faster RAM speed will also necessitate you buying extra RAM and ~$200 for faster RAM will not be worth it. And as for M.2 slots (if your current mobo is half speed M.2 slots) they won't make a difference to game performance and would only make a ~1 second difference to loading times of games, at most.