building a new pc for a friend and not sure if the gpu will work mith mobo

yes it'll work, no problem at all.

There is no performance difference between PCI-E X16 2.0/3.0, as the speed is running at the same level (X16), just 3.0 has added BIOS settings, which makes no performance difference, that card will run to it's highest capability no problem with those parts.