that's exactly what im doing lol. should getting a new mobo and 2 sticks of 8 fix the problem?
You may check the influence of 128-bit on your config by just removing the existing 8gb one. Having 8gb only for this test should work, so you can see how much of an impact just this simple trick has on your cpu performance.
Memory speed itself is also somewhat important, the 9600K, albeit already upping the clock up to 4.6ghz on stock, does support ddr4 2666 and even profits from ddr4 3000. OC of the cpu itself may add 500mhz, about 10%. The question then is, does it make sense to spend money on a z-mainboard for another +-$100 or invest the same amount into upgrading the cpu into one already running at up to 4.9ghz?