they are all compatible and 7850 is a great card and u still CAN OC a little bit but again,
nothing wrong with getting a PSU with a little more power than u need.
but still a 430W is still an awesome PSU for a 7850.
and the 24" monitor is great too!!
7850 will max anything in 1080p
and dont forget to get him a decent gamepad too!!
that would be a complete gift