Last week I looked at DDR4 memory scaling from 2133MHz to 3866MHz on the new Intel 6th Generation Core i7-6700K ?Skylake? processor. Since that article was published I?ve received a number of kind and helpful letters from the overclocking community, board makers and memory companies with ideas on how to get even better memory performance. Intel has yet to brief the media on the changes the made in the 14nm Skylake core architecture and it turns out I might have unintentionally been limiting some internal memory bandwidth by overclocking the DDR4 dual-channel memory without also overclocking the processors cache or ?Ring Frequency? as some people call it. In our original DDR4 memory scaling article the Intel Core i7-6700K Processor was overclocked to 4.6GHz, but I didn't overclock the CPU cache and left it at 4.1 GHz. The CPU Cache Frequency can be adjusted on most enthusiast-class Intel Z170 based motherboards in either the UEFI itself or on the desktop with the Intel Xtreme Tuning Utility (Intel XTU).

Intel clocks the CPU Core/Cache Frequency at 4100 MHz on the Core i7-6700K and they picked that frequency as it was best tuned to go along with the processors maximum Turbo Clock speed (4.2GHz) and the most common memory kits on the market today. Changing this value in the UEFI was very simple as I just changed the min/max CPU Cache ratio from AUTO to a higher value that I wanted. Without knowing much about the architecture I had to talk to several board makers about what they know to be safe and if higher voltages would be needed for overclocking. It turns out that the ring/cache voltage is tied into the core processor voltage on most boards, so no voltage changes should be needed for cache overclocking. ASUS was able to confirm that the CPU Core/Cache voltage is linked together on the ASUS Z170 Deluxe motherboard that I am using as a test platform. From what I have learned, the cache frequency itself should easily be increased 300-500MHz on the new K-Sku processors without breaking a sweat, but like any overclock you can go higher if you want to push it a little bit.