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Intel's Core i9-9980XE CPU reviewed

Harder, better, faster, solder

Intel's high-end desktop dominance has been under siege ever since the name Threadripper was first uttered. The blue team's first round of Core X CPUs, topping out with the i9-7980XE's 18 cores and 36 threads, held a front against the first wave of AMD's high-end Ryzens, but PC builders groused nonetheless—and rightfully so. Where did the solder that had joined heat spreaders to dies of past high-end Intel CPUs go, especially on a $2000 chip? Why did X299 motherboards have problems keeping their VRMs cool enough under extreme loads with the platform's highest-core-count CPUs? Why did quad-core parts exist for the X299 platform at all?

Next to the unrestricted, segmentation-free approach of Threadripper CPUs and the X399 motherboards, the X299 platform and the breadth of the CPUs that could light it up looked by turns stingy and scattered. The Core i7-7800X and i7-7820X offered only 28 PCIe lanes from the CPU, compared to the 44 from the Core i9-7900X and better CPUs in the lineup. The entry-level Core i7-7800X didn't even benefit from Turbo Boost Max 3.0, one of the headlining innovations of the Core X lineup. Worse, the 16 CPU-powered PCIe lanes from the Kaby Lake-powered Core i5-7640X and Core i7-7740X required motherboard makers to employ complex lane-switching schemes even on high-end mobos that seemed unlikely to ever play host to their four cores.

Intel may have had good intentions in providing builders a wide range of choices and an upgrade path in putting together high-end systems, but the initial headaches of X299 suggested that strategy had stretched the platform a bit too far.

AMD didn't stand still with its high-end desktop CPUs in the intervening time, either. The Threadripper 2990WX didn't just challenge the i9-7980XE in some workloads—it actually beat Intel's highest-end desktop chip in some tasks for less money (though not in every test). Glancing though that blow may have been, the fact that AMD was even able to lay a finger on Intel's high-end desktop performance crown was an indignity unimaginable just a couple of years ago. The ball has been in Intel's court since, and that brings us to the new range of Core X CPUs launching today.

Max 3.0
i9-9980XE 3.0 4.4 4.5 18/36 165 24.75 44 Four channels
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

Intel isn't classifying these chips as anything other than members of the Skylake family in its official materials, but that nonchalant code-naming scheme hides a range of under-the-hood improvements in the i9-9980XE and its stablemates. These chips benefit from some of the improvements in both eighth-gen and ninth-gen Coffee Lake mainstream CPUs.

First off, these new high-end chips are fabricated on Intel's 14-nm++ process. 14-nm++ allows Intel's engineers to lay down transistors that can be driven harder for better performance in exchange for only a slight increase in leakage current. In short, we can expect a better performance foundation for these CPUs without drastic increases in power consumption, and that reinforcement comes out in some minor clock-speed adjustments from top to bottom. 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). 

Indeed, the existence of the Core i9-9820X suggests the product managers in charge of revitalizing the Core X lineup couldn't keep the segmentation goblins entirely at bay. Those mischief-makers managed to get one weird chip into the new lineup. The i9-9820X has the 10 cores and 20 threads of its immediate superior, the i9-9900X, but in exchange for a $100 lower suggested price, it loses 2.25 MB of L3 cache, 300 MHz of peak Turbo Boost speed from any given core, and 300 MHz of Turbo Boost Max 3.0 speed from the two best cores on the chip. Perhaps this CPU is meant for overclockers trying to get ahold of 10 Skylake cores for as little cash as possible. For most high-end builders, though, we'd guess the extra $100 for the much-better-on-paper i9-9900X isn't going to be a major obstacle.

For overclockers who do want to try and push those 10 cores to their limit, Intel has come to its senses about the material it uses to conduct heat from chip to cooler. Following in the footsteps of the Core i9-9900K and friends, refreshed Core X CPUs enjoy the return of solder thermal interface material (TIM). In tandem with the large dies that naturally arise from putting as many as 18 cores on a CPU, that metallic TIM could let overclockers cool these chips without resorting to the risks of delidding and repasting with more thermally conductive materials than Intel's factory goop.

A conceptual view of the mesh interconnect used to join Skylake Server cores together

The benefits of big chips for heat transfer and cooling could apply to the entire Core X refresh lineup, too. You'll note that many chips in this new lineup sport more L3 cache than the 1.375 MB per Skylake Server core would naturally add up to. That's because Intel can disable cores on these chips without turning off the associated slice of L3 cache on the mesh that joins cores and shared caches together, and that fact offers a tantalizing clue as to the silicon being used to make these chips. 

As Ian Cutress at Anandtech has pointed out, the fact that refreshed Core X CPUs boast more L3 cache than active cores would normally offer—especially at the low end—suggests that Intel is using its high-core-count (HCC) Skylake Server die as the starting point for all of the chips in this lineup. Another bit of backup for that suggestion comes from the fact that all Core X CPUs now come with a 165-W TDP, a figure previously reserved for only the four highest-core-count CPUs in the Core X lineup. In tandem with solder TIM and the process improvements of 14-nm++, the use of a uniformly large die across the refreshed Core X lineup could offer better overclocking potential across the board, thanks to the fact that there's more surface area that can be joined to the heat spreader above by way of that solder.

One final segmentation demon that's been banished from refreshed Core X CPUs is the 28-PCIe-lane switch that used to get flipped on Intel's entry-level high-end parts. Every refreshed Core X part offers 44 CPU-powered PCIe lanes for motherboard makers to distribute as they please. While that figure still doesn't match the 60 PCIe lanes AMD fans can enjoy from every Threadripper CPU, across-the-board consistency from the blue team is a welcome olive branch for I/O- or peripheral-hungry builders who might not have wanted to spend extra for cores, threads, and consequent cooling hardware that might not have been needed on the road to expansion bliss.

Getting to know the Core i9-9980XE

Core i9-9980XE on the left, Core i9-7980XE on the right

Intel only sent us one chip to test today: the highest-end Core i9-9980XE. At $1979, this chip is the latest Extreme Edition standard-bearer. If you want the very best of refreshed Core X, this chip is it. Rather than the vague spec table that Intel provides, let's dig into the i9-9980XE's per-core Turbo table and see just what the combination of process tech improvements and solder buys us versus the outgoing Core i9-7980XE.

Number of cores active 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
i9-9980XE Turbo Boost speeds (GHz) 4.5 4.5 4.2 4.2 4.1 4.1 4.1 4.1 4.1 4.1 4.1 4.1 3.9 3.9 3.9 3.9 3.8 3.8
i9-7980XE Turbo Boost speeds (GHz) 4.2 4.2 4.0 4.0 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.5 3.5 3.5 3.5 3.4 3.4

Our test motherboard suggests the i9-9980XE incorporates its two Turbo Boost Max 3.0-capable cores into the up-front Turbo table of the chip, rather than leaving the operating system to work with an Intel driver to identify and pin workloads to those cores. Around the time the first round of Skylake-X CPUs launched, Intel said it was working with Microsoft to expose favored cores like those for Turbo Boost Max 3.0 to the operating system directly. Perhaps the incorporation of those 4.5-GHz bins into the Turbo table (rather than the official 4.4-GHz peak Turbo Boost 2.0 speed of the chip) is one puzzle piece in that larger effort.

From three to 12 active cores, the i9-9980XE boasts only a 200-MHz clock-speed boost over its predecessor. Once we reach 15 to 18 active cores, however, Intel seems to have taken advantage of some of the headroom the 14-nm++ process and solder TIM afford to keep Turbo Boost clocks as much as 400 MHz higher than those of the i9-7980XE. We'll have to check just how much power that move burns later on, but a 400-MHz bump across 18 cores and 36 threads is a juicy improvement. Let's see just how that improvement plays out in our test suite.