Another Intel CPU that never made it onto the shelves was the Core i5-7660X. A sample of this “stone” was lucky enough to attract a PC enthusiast from China. Intel gave it some overclocker experience, but for some reason, Intel did not sell this SKU in the end. Core i5-7660X uses Skylake microarchitecture. Manufactured on a 14nm+ process node, it is adapted to the LGA2066 slot like any other Skylake X chip. The Core i5-7660X inherits all the attributes of Skylake-X, such as support for four channels of memory (up to 128GB) and AVX-512 instructions.
So if Intel had released the Core i5-7660X that year, this processor would have been an interesting product at the time. It will not only be Intel’s first Core i5 HEDT platform processor, but also the first Core i5 SKU to support four channels of memory, and the Core i5-7660X will have six cores, six threads, and 8.25 MB tertiary cache, which are enough to conclude that the Core i5-7660X is closely related to the Core i7-7800X.
And the Core i5-7660X has a base frequency of 3.4 GHz, but its core frequency is particularly impressive. This generation of Skylake-X products can reach a core frequency of up to 4.3 GHz, while the Core i5-7660X has a core frequency of 5 GHz, which is not surprising today but was totally amazing in the past.
So you can say that the Core i5-7660X is essentially a Core i7-7800X with a higher core frequency but without hyper-threading support. They have the same 140W TDP, but by disabling hyper-threading, Intel can make the Core i5-7660X reach a higher core frequency. The Core i5-7660X offers 28 PCIe 3.0 lanes and supports DDR4-2400 memory like the Core i7-7800X. This generation of the Skylake-X family only had Core i7-7820X and later processors that supported DDR4-2666.
The reason why Intel never released the Core i5-7660X to the public is probably that AMD’s Rexroth processor came out and started a multi-core war, only the mid-range Ryzen 5 1600 has 6 cores and 12 threads, which also makes uncomfortable for the Core i5-7660X, which belongs to the HEDT platform but only has 6 cores and 6 threads.