Intel bolsters Core X CPUs with higher clocks, more cache, and solder


Along with its refreshed Coffee Lake chips, Intel announced an update to its Skylake-X CPUs for the X299 platform yesterday morning. While the underlying architecture of these parts is the same as the first round of Core i7 and Core i9 CPUs for the platform, quite a bit has changed in the way Intel manufactures and packages those CPUs.

Base
clock
speed
(GHz)
Peak
single-core
boost
speed
(GHz)
Turbo
Boost
Max 3.0
peak
speed
(GHz)
Cores/
threads
TDP
(W)
L3
cache
(MB)
CPU
PCIe
lanes
Memory
support
Price
i9-9980XE 3.0 4.4 4.5 18/36 165 24.75 44 Four channels
DDR4-2666
$1979
i9-9960X 3.1 16/32 22 $1684
i9-9940X 3.3 14/28 19.25 $1387
i9-9920X 3.5 12/24 $1189
i9-9900X 10/20 $989
i9-9820X 3.3 4.1 4.2 16.5 $889
i7-9800X 3.8 4.4 4.5 8/16 $589

As with Intel's unlocked mainstream desktop parts, one of the loudest complaints about Skylake-X CPUs regarded the effectiveness of the paste-type thermal interface material the company began using in lieu of solder on its first run of those chips. Indeed, we've rarely found ourselves limited by the underlying silicon when overclocking our Skylake-X CPUs—the wall has been entirely thermal. With its refreshed Skylake-X CPUs, Intel has resumed soldering the die to the integrated heat spreader (or IHS). That move could finally allow overclockers to reach the limits of refreshed Skylake-X parts without the hassle of popping off the IHS and applying more effective thermal interface material of their own.

Refreshed Skylake-X parts have also moved to Intel's refined 14-nm++ process technology. The apparent benefits of this move emerge in some small spec adjustments from the first round of Skylake HEDT parts. Intel now specifies a Turbo Boost Max 3.0 speed of 4.5 GHz across the board for these chips (save for the Core i9-9820X and its victim-of-segmentation 4.2-GHz TBM 3.0 speed). Depending on the chip in question, peak Turbo Boost speeds have also increased anywhere from 100 MHz to 200 MHz (again excluding the odd-man-out i9-9820X). 

Base frequencies for these parts have also increased across the board, but those increases likely won't matter to enthusiasts installing these CPUs in well-cooled systems. Intel has also increased TDPs for all of these parts to 165 W, a move that could be an effort to allow the chips to take greater advantage of the performance on offer from the improved process. Taken together, those increases in clock speed, process, and thermal headroom could offer small but welcome improvements in performance in lightly threaded and multithreaded workloads alike. We'll have to wait until we see the full Turbo Boost tables for these parts to be sure, though—information that Intel remains stubbornly resistant to disclosing.

Another change for refreshed Core X-series chips is that L3 cache sizes on several models have increased. Skylake-X cores each have 1.375 MB of L3, and Intel can disable some of those cores on a die while leaving their shared L3 caches available to the active cores on the chip. As Ian Cutress at Anandtech points out, the fact that Intel is now enabling more cache than there are active cores on some refreshed Core X chips means the company is likely flipping switches on its high-core-count Skylake Server silicon to make these consumer parts now, rather than repackaging its low-core-count chips. That fact could also help to explain the higher TDP of refreshed Core X CPUs in general.

An X299 pain point that AMD has been probing with sharp instruments is Intel's choice to segment the number of PCIe 3.0 lanes available from the CPU. High-end desktop users who need plenty of PCIe lanes for storage or expansion cards can rejoice, as Intel is dropping its 28-lane and 44-lane product tiers. All refreshed Skylake-X CPUs can deliver 44 lanes of PCIe 3.0 connectivity directly to expansion cards and storage devices.

One X299 limitation that's sticking around is the platform's 128-GB maximum memory capacity. Intel also isn't permitting motherboard makers to add ECC RAM support to their boards, as was sometimes possible with the X99 platform. Users who need the assurance of ECC will still need to use Xeon W platforms, not Core X.

Intel will be releasing its refreshed Core X chips next month.

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