When Intel launched its new high-end desktop platform a few weeks ago, we were provided with Core-X CPUs from quad cores on the latest Kaby Lake microarchitecture, and 6/8/10 core parts on the Skylake-SP microarchitecture derived from the enterprise line and taking a different route to how the cache was structured over Skylake-S. At the time we were told that these latter parts would be joined by bigger SKUs all the way up to 18 cores, and up to $2000. Aside from core-counts and price, Intel was tight lipped on the CPU specifications until today.

Skylake-X goes HCC

The original Skylake-X processors up to 10 cores used Intel’s LCC silicon, one of the three silicon designs typically employed in the enterprise space, and the lowest core count. The other two silicon designs, HCC and XCC, have historically been reserved for server CPUs and big money – if you wanted all the cores, you had to pay for them. So the fact that Intel is introducing HCC silicon into the consumer desktop market is a change in strategy, which many analysts say is due to AMD’s decision to bring their 16-core silicon into the market.

Both the new HCC-based processors and the recently released LCC-based processors will share the same LGA2066 socket as used on X299 motherboards, and all the processors will differ in core count, with slight variations on core frequencies, TDP and price.

The Skylake-X line-up now looks like:

Skylake-X Processors
  7800X 7820X 7900X   7920X 7940X 7960X 7980XE
Silicon LCC   HCC
Cores / Threads 6/12 8/16 10/20   12/24 14/28 16/32 18/36
Base Clock / GHz 3.5 3.6 3.3   2.9 3.1 2.8 2.6
Turbo Clock / GHz 4.0 4.3 4.3   4.3 4.3 4.3 4.2
TurboMax Clock N/A 4.5 4.5   4.4 4.4 4.4 4.4
L3 1.375 MB/core   1.375 MB/core
PCIe Lanes 28 44   44
Memory Channels 4   4
Memory Freq DDR4 2400 2666   2666
TDP 140W   140W 165W
Price $389 $599 $999   $1199 $1399 $1699 $1999

Along with this, we have several release dates to mention.

  • The 12-core Core i9-7920X will be available from August 28th
  • The 14-18 core parts will be available from September 25th (my birthday…)

On the specification side, the higher-end CPUs get a kick up in TDP to 165W to account for more cores and the frequency that these CPUs are running at. The top Core i9-7980XE SKU will have a base frequency of 2.6 GHz but a turbo of 4.2 GHz, and a Favored Core of 4.4 GHz. The turbo will be limited to 2 cores of load, however Intel has not listed the ‘all-core turbo’ frequencies which are often above the base frequencies, nor the AVX frequencies here. It will be interesting to see how much power the top SKU will draw.

One question over the launch of these SKUs was regarding how much they would impinge into Intel’s Xeon line of processors. We had already earmarked the Xeon Gold 6154/6150 as possible contenders for the high-end CPU, and taking the price out of the comparison, they can be quite evenly matched (the Xeons have a lower turbo, but higher base frequency). The Xeons also come with multi-socket support and more DRAM channels, at +60% the cost.

Comparing against AMD’s Threadripper gives the following:

Features Intel Core
Intel Core
AMD Ryzen
Threadripper 1950X
Platform X299 X299 X399
Socket LGA2066 LGA2066 TR4
Cores/Threads 18 / 36 16 / 32 16 / 32
Base/Turbo 2.6 / 4.2 / 4.4 2.8 / 4.2 / 4.4 3.4 / 4.0
GPU PCIe 3.0 44 44 60
L2 Cache 1 MB/core 1 MB/core 512 KB/core
L3 Cache 24.75 MB 22.00 MB 32.00 MB
TDP 165W 165W 180W
 Price $1999 $1699 $999

We fully expect the review embargoes to be on the launch dates for each CPU. Time to start ringing around to see if my sample was lost in the post.

Related Reading

Update on 8/8:

Due to some sleuthing, PCGamer managed to obtain turbo frequencies based on per-core loading. I'm surprised Intel doesn't give this data out like candy when the products are announced, but we're glad to have it nonetheless.



View All Comments

  • nevcairiel - Tuesday, August 8, 2017 - link

    The turbo charts suggest that the 18-core will turbo all cores to 3.4 GHz, but that might exceed TDP in stress-testing situations - although someone building such a system better include a good cooler so they can exceed TDP and possibly even turbo higher then that. Reply
  • ddriver - Tuesday, August 8, 2017 - link

    If that excludes AVX, then those frequencies do not matter for prosumers. Every prosumer workload out there uses the vector units. The ALU is probably not more than 10% of the entire core performance, and is used mostly for program flow rather than actual data computations. Reply
  • nevcairiel - Tuesday, August 8, 2017 - link

    AVX/AVX2 doesn't really need that strong of a downlock anymore. AVX512 does, however, but it also offers quite a lot of throughput, so its usually still a net-gain.

    I can only judge my 7900X with OC settings (which many motherboards even apply automatically as long as thermals permit), where AVX2 only needs a -2 offset, and AVX512 needs -7 to -9, depending on what turbo you use as a base.

    Until these high-core-count CPUs are properly vetted, its impossible to say which typical clocks one can expect in the different workloads, but its definitely going to be above the "base" frequency at all times.
  • Lolimaster - Monday, August 7, 2017 - link

    You can perfectly do all of that with base clocks of the Ryzen 1700X, TR 1950X has that same advantage with twice the cores. There goes your jack of all trades. Reply
  • drothgery - Monday, August 7, 2017 - link

    None of Intel's current 16-core (or greater) offerings have a base clock > 2.6 GHz. In fact, nothing with over 12 cores does. Reply
  • nevcairiel - Tuesday, August 8, 2017 - link

    The base clock isn't all that relevant - what is relevant is the typical clocks its running at in typical workloads. "Base" is a sort of worst case situation, but no typical Intel CPU runs on their base clock much.

    According to the graphs posted above, even the 18 core should turbo to 3.4GHz all core by default, which can be increased with decent cooling. And ST workloads where clock matters the most won't run all the cores and clock higher as well.
  • nevcairiel - Tuesday, August 8, 2017 - link

    .. also, you are wrong. The 16-core itself even has a base of 2.8 GHz and the 13 core even 3.1 GHz - only the 18 core has a base of 2.6 Reply
  • nevcairiel - Tuesday, August 8, 2017 - link

    *14 core. Edit button where are thou. Reply
  • drothgery - Tuesday, August 8, 2017 - link

    Eh, I looked at the latest-version Xeon family pages at ark.intel.com when I posted that comment. Reply
  • Ian Cutress - Wednesday, August 9, 2017 - link

    Check our Skylake-SP vs EPYC review for a full breakdown of all the Sky-SP CPUs Reply

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