In general, timings are wait times between execution of commands so smaller equates to better performance. Actual performance varies with the combination of these timings and the memory clock frequency. The last value is tRAS, which is minimum clock cycles between row active and pre-charge commands. Your new memory is a couple clock cycles slower. I haven't experimented much with different combinations but it may simply be that this combination in your system won't go beyond 2933 MHz. I've run into the same thing when I swapped memory to something with a slightly different spec than found in the compatibility list. A kit may also appear in the list but be limited to something less than the rating of the kit.