What kind of monitor are you using? If its only 60hz the lag you are noticing could be frame tearing....
Also what gpu are you using? If its semi-new the cpu will always be the bottle neck in a game like dota 2.
I don't it's as much of an issue as it would be if it were something like a non-K series intel chip.... I think anyone who actually cares and/or notices is most likely over clocking anyways. Though I haven't jumped on the Ryzen boat yet everyone I know personally who owns one has overclocked it beyond its precision boost/xfr anyways. Even someone I know who is running it on the stock cooler was able to get his R5 1300 to 3.8.... Also (I'm assuming not though it happens to all of us, you just miss that one setting) do you have your board or power management in any kind of gaming or high performance mode? I've heard that it can mess with XFR.
Obviously these are just guesses but the consensus seems to be some kind of 750 ti which would make sense it was very popular for budget systems about 2 years ago.
I would ask the seller.
FX 8300 both old now, but the 8300 can be oc'd and will work much better for gaming. Just make sure you have a gpu as it doesn't have an igpu. As I said both are old now, but between those two.... The FX 8300 is far superior.