CORRECTION: Due to a reporting error, an earlier version of the story misidentified the product that has been retired. It is the Skylake-C and not the Broadwell-C that has been discontinued. Changes have been made throughout the story to reflect the change.
Products are usually cancelled because the vendor struggles to make them work properly, but Intel has cancelled one chip for undisclosed reasons that may be more financial than performance-related.
A little background. Back in June, Intel announced a processor branded as Broadwell-C. It would be a Broadwell processor, which was a die shrink of the Haswell from 2013, but with Intel's best Iris Pro graphics and an on-package eDRAM cache.
eDRAM, or embedded DRAM, is used in microprocessors to provide DRAM-level performance on the die of the CPU or SoC. It offers wider buses and higher speeds than SRAM, which is typically used in CPUs for the caches. It's used in a wide variety of processors, from IBM's Power 7 processor to the AMD SoC in the Xbox One and PlayStation 4. It also costs a little more than SRAM but not a lot.
The Tech Report tested the processor alongside older high-end Intel processors and Skylake, and found that Broadwell-C, despite being based on a two-year-old CPU design, outperformed the best of Intel's newly-launched Skylake processor, the Core i7-6700, and creamed the older chips thanks in part to an insane 128MB L4 cache and its much larger GPU.
It's a bit of a mismatch to compare the Skylake 6700K design, for enthusiasts, and the 5775-C, which is meant for content creators and gamers. But people tend to blur the lines between products despite where Intel wants them to go. What the 5775-C shows is the potential for a Skylake-C to be a real killer chip, even beyond what Skylake-K does.
Unfortunately that won't happen. Intel has decided not to make a Skylake-C processor. There will be a broad range of Skylakes for handhelds, tablets, laptops and desktops, many of which are already announced, but there will not be a Skylake-C.
So that means fewer CPUs per wafer, and with the eDRAM comes increased cost and potentially lower yields. That means a combination of increased cost and lower yield. Intel has had enough headaches with 14nm as it is, and there is the upcoming Kaby Lake processor, which we don't know much about. So I can see why it was killed.
Intel did confirm to me that the part was cancelled but would not give an official reason beyond it was responding to market demands.