Intel Comet Lake CPUs: Rumors, All We Know

Intel's new Comet Lake processors are coming to laptops and desktops soon, with flagship desktop models topping out at 10 cores and high-performance notebook models wielding eight cores.

Changing a CPU roadmap is like steering a supertanker -- big course corrections take time. Due to the typically multi-year process of developing and fielding a new processor, Intel's response to AMD's Ryzen CPUs has been slow and exacerbated by its tardy jump to the 10nm node.

Intel's answer to Ryzen began with the Coffee Lake processors, whose bump up to six cores edged Intel closer to matching Ryzen's eight-core onslaught, followed a year later by Intel's new eight-core Core i9 processors that finally leveled the playing field, at least from a core count perspective.

But AMD is already moving to the 7nm manufacturing process with its new Ryzen 3000-series that will debut in mid-2019. These new processors come packing eight cores paired with the new Zen 2 microarchitecture (microarchitecture refers to CPU core design), and according to a demo by AMD CEO Lisa Su at CES 2019 showing the processors match the Intel Core i9-9900K's performance (but with lower power consumption), they'll be brutally competitive against Intel's revamped Coffee Lake processors.

Intel recently released its Coffee Lake Refresh processors on the 14nm process, but its 10nm Ice Lake processors aren't expected until later in 2019, although most industry speculation points to early 2020 for mass availability of desktop models. That leaves Intel with a gap to plug if it wants to grapple with the forthcoming Ryzen 3000 series.

That response comes in the form of Comet Lake, which appears to be a refresh of the Coffee Lake refresh. Intel hasn't officially revealed its plans for the Comet Lake processors, or even their very existence, but concrete information has already come to the surface. There are still several unanswered questions, but let's take a look at what we know, and what we don't.

Cratering In

Word of the Comet Lake (CML) processors surfaced in late 2018 in a post from an anonymous Chiphell forum poster that claimed the 10-core, 14nm chips were discussed at a partner event. As with most early mentions of a new processor, there was little verifiable information to back the claims.

That changed in early March 2019 as the Comet Lake PCI CPUIDs, used for identifying the processor to an operating system, were listed on freedesktop.org, an organization that helps ensure interoperability for Linux-based operating systems. This posting gave us little information to work on, aside from the note that the processors wielded Intel's Gen9 graphics, which implies the chips come with some variant of the 14nm process. The listing also states that Comet Lake "comes off" the Coffee Lake family, which suggests the chips feature that same microarchitecture.

The most substantial information came with the inclusion of new graphics drivers in the Linux kernel driver and coreboot, previously known as LinuxBIOS. This listing revealed the processors would come in U-, ULX-, Y-, S- and H-Series variants and confirms the core counts and graphics configuration (for instance, a 4+2 listing confirms four host processor cores and a GT2 graphics unit and so on).

The S-Series comes as yet another refresh of the Coffee Lake Refresh processors for the mainstream desktop. These desktop processors mark Intel's first 10-core model for its mainstream platform, a new high watermark and also include six-core models that will likely replace or augment the Core i5 and i7 series.

The lack of an eight-core model implies that Intel will not replace its eight-core, 16-thread i9-9900K. Intel could also choose to reformat its entire lineup, as it has done with the Coffee Lake processors, and bring 10-core, 20-thread processors to the Core i9 series, 10- =core Core i7 models without Hyper-Threading and then bump up the Core i5 series to eight-core, eight-thread. That would mean the company would have to bring the Core i3 models up to six-core, six-thread, and finally bring the Pentium lineup to a quad-core design. 

The mobile variants (U, Y, H) come to market as updates to the Whiskey Lake and Amber Lake processor family. These models range from dual-core models for the U-series to eight-core models for the H-Series. The six core U-series models mark a new high core count for the ultra low power segment, while eight cores is a new height for the high-power H-Series.

Comet Lake Graphics

The driver listings indicate the Comet Lake chips come packing Intel's Gen9 graphics, which could be a basic listing of Intel's most recent Gen 9.5 graphics engine. Gen 9.5 integrated graphics power Intel's UHD Graphics engine on the current line of Coffee, Whiskey and Amber Lake processors.

The chips come with "+2" GT2 graphics configurations, which denotes three Gen 9.5 subslices featuring eight execution units apiece (EU), totaling 24 EU. The GT2 graphics designation also tells us the processors will feature either UHD Graphics 620 or 630 engines, with the 630 graphics having slightly higher frequencies.

Intel's current modular graphics engine debuted with its Skylake processors but has been improved over subsequent generations, with the latest improvements consisting of minor improvements to the display and media blocks. The underlying design has been present throughout Intel's 14nm journeys, once again implying the Comet Lake processors remain on 14nm. It's notable that Intel's only shipping 10nm processors, which hail from its failed Cannon Lake excursion, feature disabled Gen10 graphics.

Comet Lake Architecture

All signs point to the Comet Lake processors featuring the 14nm process, partly because they are a stopgap to vie with AMD's Ryzen 3000 series processors until Intel's 10nm Ice Lake processors come to market in late 2019, but we aren't sure which iteration of the 14nm process will be under the hood.

Intel stepped through multiple enhancements of the 14nm process, yielding a 70 percent performance increase since its debut in 2014, with some inter-node enhancements sporting a "+" suffix. As such, Intel progressed through 14nm, 14nm+, and 14nm++. However, the company no longer uses the + suffix to denote new improvements, so the Comet Lake processors will likely come branded as plain old 14nm, though they would comprise the fifth (or sixth?) revision of the silicon.

Intel has iterated on its Skylake microarchitecture incessantly, largely due to its previous policy of locking new architectures behind jumps to smaller process nodes. That obviously restricted the company's progress while it is mired on the 14nm process due to nagging delays to its 10nm processors. That means that its new CPU core designs have traditionally required a move to new, smaller manufacturing processes. That approach became a liability as Intel encountered massive delays with its 10nm process.

Intel tells us it will now design new microarchitectures to be portable between nodes. That will allow the company to move forward even if it encounters roadblocks on its path to smaller transistors. The Sunny Cove microarchitecture is the first new design that can be used on multiple nodes, and even though Intel has stated the new core will debut on the 10nm node, the design will also port over to future 7nm chips. However, this microarchitecture will not come to 14nm processors.

That means the probability of Comet Lake coming with the fourth generation of the Skylake microarchitecture is high.

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*Images courtesy WikiChip

Intel's recent core count increases have come as a byproduct of simply adding more cores to the existing design that still wields the ring bus interconnect. The ring bus is a high-speed pathway that ties together the cores and cache together with the various uncore components, such as the memory and I/O controllers.

The ring bus has proven to have limited scalability, so Intel moved forward with its mesh architecture for its Xeon Scalable processors. This new design eliminates the need for a dual ring bus design, but, while it's possible, it isn't likely that Intel has undertaken the significant microarchitectural redesign required to support the new interconnect. Instead, the Comet Lake processors likely still come with the ring bus design extended out to add two more cores to the design (imagine two more cores added to the graphics above).

There isn't any concrete information regarding the Comet Lake memory subsystem, but Intel will likely stick to the dual-channel memory allotment that it has used for its mainstream platform. This could prevent memory throughput challenges, as the ring bus does have limited scalability and feeding the cores with enough data from memory could strain the throughput of the interconnect. There have been rumors that the design includes a dual ring bus with intermediary buffer switches, much like we see on older Xeons, but that isn't likely given that Intel would probably move forward to its next-gen mesh architecture instead of resurrecting a now-obsolete interconnect design.

Intel's Core i9-9900K comes with a beefy 16MB of L3 cache split out into 2MB slices per core. Naturally, adding two more cores to the design would bring along an additional 4MB of L3 cache, so the deca-core Comet Lake model could come with 20MB of L3 cache.

Comet Lake Motherboards

Much to the dismay of upgrade-loving enthusiasts, Intel has traditionally transitioned to a new chipset every second generation. This approach does afford the company more flexibility as it adds new technologies to its platforms, but the company may forgo the practice with the Comet Lake platform and allow compatibility with existing chipsets.

When Coffee Lake debuted, Intel beefed up the package power delivery to the 1151 v2 socket to support the six-core Coffee Lake processors. Z390 motherboards followed for the Coffee Lake refresh models, but even the eight-core Core i9-9900K retained backward compatibility with the previous-gen Z370 motherboards. That implies that Intel laid the groundwork for its eight-core Coffee Lake refresh models long before they came to market, and perhaps the company over-provisioned the power delivery enough to support ten-core models, too.

Or Intel could proceed with its tactic of frequent motherboard refreshes and introduce a new chipset. We could even see a new CPU socket. Queue the Z470/Z490 motherboards? For now, we simply don't know.

Comet Lake Power Consumption

More cores equate to more power consumption, and Intel's current flagship Core i9-9900K already pushes the needle up to 232 watts during stock operation. That high peak power consumption would be exacerbated by the addition of two extra cores with the 10-core Comet Lake flagship.

From a high level, the chip splits power up between the processing cores, memory and the package, with the latter two comprising roughly five percent of the power consumption under load. Working out the basic math, if all other factors remain equal, we could see up to 288 watts under load with the 10-core Comet Lake models.

Power equates to heat, so Intel will have its hands full dissipating that amount of heat from the die to the integrated heat spreader. That means we'll see the company continue using solder TIM (sTIM) to improve thermal transfer efficiency. Intel lists a 130W cooler as an entry-level solution for the eight-core Core i9-9900K, but expect that requirement to move forward even more. The ten-core Comet Lake processors could even be the first mainstream processors that Intel recommends a water cooler as the minimum acceptable cooling solution, much like its Skylake-X processors.

In the past, Intel has also had to dial back its base clock speeds as it increases core counts, but it maintained the same 3.6 GHz base clock for the six-core -9700K and the eight-core -9900K, so we could see a similar range for the new 10-core model.

Intel's real gains in clock speeds have come in multi-core workloads, where the CPU drops back into lower clock speeds as more cores become active. The eight-core 9900K surprisingly has a higher dual-core boost than its six-core counterparts, and multi-core turbo frequencies are higher, too. Hopefully we will see a continuation of this trend with the ten-core Comet Lake model. 

Comet Lake Price

With an ongoing shortage continuing to push Intel's notoriously high pricing even further into the stratosphere, it's hard to gauge where pricing for the Comet Lake models will land. The new six-core models will likely debut at similar pricing to their counterparts, but the 10-core model will undoubtedly set a new high pricing watermark for the mainstream desktop.

You can find the Core i9-9900K at retail for ~$525 (£509), and logically we would expect the addition of 25 percent more cores to result in a commiserate increase in pricing. The Core i9-9900K retails for ~$65 per core, and simple math dictates that would result in a street price of $656 (or equivalent in £) for the new flagship Comet Lake processor.

Of course, it isn't that simple. Intel's 14nm process is incredibly refined, meaning the company is likely experiencing fantastic yields that reduce manufacturing costs. However, current pricing is inflated due to shortages that are expected to abate in the latter half of the year, so we could see lower per-core pricing at the tail end of the year.

Comet Lake Release Date

Even though they aren't expected in significant quantities for the desktop until early 2020, Intel's Ice Lake is officially due to arrive in late 2019 on the 10nm process, so the stop-gap Comet Lake processors should arrive near the middle of the year. That aligns perfectly with the Computex time frame, though the processors may not come to market in significant quantities until later in the year. We should expect more information, if not the formal launch, of the Comet Lake processors at Computex.

Play 14nm Again, Sam

Comet Lake could help shore up Intel's defenses against the new Ryzen lineup, finally beating AMD's core counts, but whether they'll maintain a lead over the Ryzen 3000 series remains an open question–AMD has left open the possibility that its new chips may come with more than eight cores.

Intel's trials and tribulations with the 10nm process are well-documented, but the summit is in sight. As such, it looks like the Comet Lake processors will serve as the swan song for 14nm on the desktop. Intel has done an enviable job pushing the limits of the 14nm process and extracted a 70% increase in performance since its debut, but it has surely entered the land of diminishing returns.

With 14nm nearing the end of its evolutionary curve, and AMD pressing forward with TSMC's 7nm process powering its Ryzen 3000-Series processors, Intel turned to architectural enhancements to grapple with the Zen-based processors. That is great for us enthusiasts, but it leaves Intel open to a potential upset. More cores will equate to more processing grunt power, and we expect the Comet Lake processors will continue to press Intel's advantage in lightly-threaded tasks, but these things come at the cost of exorbitant pricing and power consumption.

Intel's pricing continues to be a thorn in its side, particularly as it grapples with a shortage of production capacity, so a win on the performance front might not equate to a thorough win in the market. TSMC's 7nm process, while more expensive to develop than prior nodes, does bring the promise of lower pricing along with it. That plays well to AMD's reputation for being the value king, but the 7nm process should also halve power consumption under the right circumstances. Even with a 14nm I/O chip sucking power, Ryzen 3000's 7nm compute dies should sip power, giving the company yet another edge as Intel turns the power up on its Comet Lake processors.

All this means that Intel's refresh of the Coffee Lake refresh might not be that refreshing after all in terms of pricing and power consumption. Ten Intel cores will be sure to deliver an impressive amount of horsepower to the mainstream desktop, further blurring the lines between the mainstream and high-end desktop lines, but this story is far from over. We'll update this post as new information comes to light.