Help me build a pc as a gift for my friend

I want to surprise my friend with a new pc. We really love to play games togheter, no matter the genre or gameplay, its more about hanging out rather than the games themselves.

The rhing is, his pc is really low (3 gigs of ram, core 2 duo etc) so we are a bit limited. Thus i want to come up with something not so expensive cus my budget is not that great (and i wouldn’t want to gift him something incomplete since he doesn’t have enough money for pc parts).

Do you have any suggestions what could i get for ~500$ tops? It doesn’t have to be able to run modern games, but let’s say at least 2016 titles