You're best move IMO is to pull those 3 out, sell them, and then pickup 2x8gb 3600mhz modules from crucial. (i suggested 2x8gb since likely the price you might get for the 3x 2400mhz modules should provide enough to get a good set of 2x8) in my opinion, yes it is too slow. if you overclock that ram to 3200Mhz but the timing also goin to slower
eauYE.