The link you provided is relying to much on single-thread performance, if you look at those CPU on OVERALL performance the FX is much better than the core i3 even at stock speed, mostly in well multi-threaded games, here are BF4 and Cysis 3 for example, the FX-6300 is holding up quite nicely with the moderns core i5 here :
This is the reason why the FX-6300 should always be recommanded over the core i3, it will do much better in modern games, except single-threaded games like skyrim or planetside 2 in wich it gets crushed..