Intel isn’t going to be launching a 28-core 5GHz processor this year after all

Earlier this week, Intel showed off a product coming in the fourth quarter of this year: an enthusiast-oriented 28-core processor running all cores at 5GHz. This combination of clock speed and core count would put it head and shoulders above any other processor on the market, so the demonstration was more than a little surprising.

It now turns out that Intel forgot to mention an important detail: the 5GHz processors were overclocked, a lot, using chilled water coolers capable of handling thermal loads of up to 1.77kW. The real chips that ship won’t be coming from the factory at 5GHz, and it’s going to take a lot more than a big heatsink and a couple of fans to get them running that fast.

Aside from the core count and release window, Intel has confirmed one other fact about these 28-core chips: they’re built on some variant of its 14nm process. They also use the enormous LGA3647 socket (that’s 3,647 pins) used by some Xeon processors, and they have six memory channels. We don’t know what platform/chipset this will use (though it’s likely to be a close relative to the comparable server platform). And we don’t know what its regular clock speed will be.

Reasonable speculation is that this chip will be taken from the Skylake-SP family. Skylake-SP (for “scalable processor”) is the variant of the Skylake core designed for processors with more than eight cores: instead of arranging the cores in a ring, they’re organized into a grid, which generally provides better scaling as the number of cores goes up, albeit at the expense of a more complicated design. Skylake-SP is used for the Xeon-SP line, and its close sibling, Skylake-X, is used for the X-Series enthusiast platform. Current Skylake-X chips lack QPI interconnects, ECC memory, and six memory channels that Skylake-SP has (they only use four), but they add overclocking.

There are three Skylake-SP dies, called LCC, HCC, and XCC (for low, high, and extreme core counts), with 10, 18, and 28 cores, respectively. Currently, there are Xeon-SP processors using all three variants. Skylake-X processors are presently only LCC and HCC. The new chip looks like it’s going to be an XCC Skylake-X.

There’s a possibility, however, that it won’t be Skylake-X at all, but rather Cascade Lake-X. Cascade Lake is an incremental revision to the Skylake-SP/X platform: it adds some extra AVX512 instructions, it should include hardware fixes for Spectre and Meltdown attacks, and it should support faster memory. It will be built on Intel’s “14nm++” process, compared to the “14nm+” process used for Skylake-SP/X, which should offer reduced power consumption.

Either way, this kind of chip won’t come cheap. The 28-core Xeons start at about $8,700. An X series version will likely cost less (because Intel can use ECC support to protect its Xeon margins) but will still slot in comfortably above the $2,000 mark for the top-end HCC Skylake-X. Who would buy such a thing? Some will likely go to the rich kids who just have to have the latest and greatest; others will be snapped up by high frequency traders running custom-built, overclocked, liquid-cooled machines for the very fastest single system performance they can get.

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