Why? Because the boost to 4.2Ghz to all cores under load. Also check out the follow benchmarks. Look at the significant difference between 6700k and the newly released 9700k.
Also for the M2 slot, no that's not true. My M2 slot can only handle PCIe. Stop spreading lies.
I wasn't comparing the 6700k to the newer processors. I was just saying that it's a waste of money to buy an overclockable intel cpu and z series overclocking motherboard and to not overclock. Also I looked up your motherboard and I stand corrected. I was unaware that there were motherboards that only supported NVMe. I know that older boards with m.2 were often sata only. Most m.2 nowadays supports both. So my mistake.