Yes, not so much in gaming, but in other areas, gaming primarily just uses DRAM as a conduit, when doing things like Video, imaging, CAD, etc, alot is actually done in the DRAM itself. With Z87 and Haswell, the CPUs have a native Mem freeq of 1600 so don't want lower than that, and Haswell scales to DRAM very well so it using faster (higher freq DRAM very well. The K CPUs are the unlocked, easily OCed CPUs of the Haswell line. And yes the MHz ratings does affect performance, especially with memory centric apps, the higher the freq or MHz, the more bandwidth is used at a time