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Is Intel's new $539 Core i9-11900K desktop CPU made of silicon? Yes, of course it is. Does that mean, by extension here in 2021, it might end up tricky to find at Intel's recommended pricing? Very possible. The demand for high-end component hardware is practically baked in these days. So the Core i9-11900K, Intel's latest flagship processor and the head of its 11th Generation "Rocket Lake" line, should sell well. But it is not the rabbit that the chip giant needs to pull out of its hat after a few years spent trailing AMD in CPU innovation and raw performance. It's merely a pedestrian showing at a time when real magic is necessary to change the CPU conversation.

The Core i9-11900K, while impressive in single-threaded tasks, in our early tests ran too hot, too power-hungry, and not stable enough under stress to remain competitive with AMD's Ryzen desktop-CPU offerings, or even Intel's own previous-generation CPUs, such as the 10th Generation Core flagship, the Core i9-10900K. The eight-core, slightly cheaper AMD Ryzen 7 5800X proves to be stiff competition for Intel on both single-core and multicore tasks, while the cheaper Intel Core i7-11700K, also with eight cores, rivaled our test sample when benchmarked in a similarly configured prebuilt MSI desktop. The slightly better single-core boost under specific thermal scenarios, which is exclusive to the Core i9-11900K, won't be enough to sell most buyers on this chip versus other options on the market with the same core count, though this dynamic could shift more in the Core i9's direction as Z590 motherboards gain more stability with it over the next few weeks and months.

Intel Core i9-11900K Specs: An On-Paper Paradox

Even on paper and in pure specs, the Intel Core i9-11900K shows a bit of an off-kilter loadout and a regression in a key area: core and thread count. Check out these specs and see if you can spot what we're talking about...

Notice anything missing versus the Core i9-10900K? Like, say, two cores? No, you don't need to get your eyes checked; Intel indeed has removed two cores from its top-end chip in the consumer Core i9 line, versus the Core i9-10900K. The company added two when it went from the 9th Generation flagship Core i9-9900K (and Core i9-9900KS) to the Core i9-10900K. The fab giveth, and the fab taketh away.

According to Intel, its engineers found that eight cores is the "sweet spot" for most enthusiasts who use Intel's high-end desktop CPUs. That's even in the face of the 12-core/24-thread Ryzen 9 5900X ($549.99 MSRP), which has been hard to find on every major retailer's website since it launched last November. That list price may be questionable, as the chip has largely been made of unobtanium since launch, but a theoretically like-priced chip with a massive 50% more cores is hard to ignore.

There is some merit to Intel's decision to cap the Core i9-11900K at eight cores. At this point in the desktop CPU game, most PC enthusiasts buying an Intel desktop CPU at this level will fall into the camp of "gamers eager to squeeze out every frame," versus that of "pro content creators who need every core they can get." The creator crowd has been seized tight by AMD's Ryzens at the moment, so it makes sense why Intel is comfortable being more conservative with its core count in the Core i9-11900K. Games can absorb benefits from only so many cores (six tends to be the max, even for AI-heavy tasks like computing turns in Civilization VI), and the Rocket Lake line is still built on another refined version of Intel's long-running 14nm process technology, as opposed to AMD's 7nm process used in its late-model Ryzens. Something had to give to get another generation out of it.

Keeping the chip to just eight cores allows for more thermal wiggle room. and by extension also enables Intel to hit higher single-threaded boost speeds, with the Core i9-11900K rated for a 3.5GHz base clock and a 5.3GHz boost clock. Note: This boost clock is only on a single, predetermined core, and it will activate at that boost speed once the parameters for an increasingly convoluted core-acceleration strategy from Intel are met.

"Convoluted," indeed may be an understatement when talking about high-end Intel chips' thermal and clock-speed management systems. Let's talk about Intel's core-accelerating TurboBoost and its several additional flavors. This time around, Intel has branded its latest on-board boost technology for its Core i9 line as Adaptive Boost Technology (ABT), not to be confused with the Thermal Velocity Boost (TVB) technology found in some 10th Generation Core "Comet Lake" chips. And that itself should not be confused with TurboBoost Max 3.0.

For TVB, the board "opportunistically and automatically increases clock frequency above single-core and multi-core Intel Turbo Boost Technology frequencies based on how much the processor is operating below its maximum temperature and whether turbo power budget is available." That frequency gain, as well as the duration of the gain, is dependent on the workload, the capabilities of the processor, and the processor cooling solution.

Confused? Take a look at Intel's illustration below to get a clearer picture of what we're talking about...

(Image Credit: Intel)

Yeah, it's a lot to grok. Adaptive Boost Technology is rather esoteric stuff. It activates when, and I quote: "When in a turbo mode, if three or more cores are active, the processor will attempt to provide the best frequency within the power budget, regardless of the TB2 frequency table. The limit of this frequency is given by TB2 in two-core mode. ABT overrides TVB when three or more cores are active."

If you didn't catch all that on the first pass, don't worry about it. We're not even sure Intel actually expects you to. Intel's push to get as much juice out of its 14nm lithography (now built on its latest "Cypress Cove" microarchitecture, backported from the 10nm "Sunny Cove" first seen in its "Tiger Lake" mobile chips) has led us here, where nearly every possible power state of the CPU also comes with a type of boost attached and everything is being optimized to the nth degree.

In so many words, in the case of high-end Rocket Lake chips, this means the processor will apply an extra boost to the two highest-quality cores on the chip when it detects that the chip is within an Intel-predetermined thermal limit of safety to do so. And in even fewer words? "Chips go faster in tasks that tax one or two cores, and AMD's Precision Boost 2 already did it in 2018."

A New IGP, Plus a New PCI Express

So, enough with the iterative stuff, let's move on to the bigger changes around Rocket Lake.

A major upgrade for Intel this time around is on the side of integrated graphics. The Intel Core i9-11900K comes with the company's new Iris Xe UHD Graphics 750 silicon. Though we didn't run any benchmarks on the integrated graphics processor (IGP) of the Core i9-11900K (partly because of time constraints, but mainly because few buyers will shop for this chip and not pair it with a graphics card), we recommend hopping over to our review of the Core i5-11600K to see just how much of an improvement gamers can expect. (Spoiler: It doubles many of the results we saw on UHD Graphics 630, but it still trails the AMD Ryzen 5 3400G in peak frame rates.)

For those looking for an IGP that can just drive a display, however, the Iris Xe UHD 750 will support one 4K (4,096-by-2,303-pixel) display up to 60Hz, or up to three displays in total at lower resolutions.

Here's a look at the full Rocket Lake stack, with the Core i9-11900K at the top...

We left off Intel's "T"-class Rocket Lake chips, low-power-consumption models mainly of interest to system OEMs. As you can see, as in the previous generation. Intel is also offering non-"K" versions of the various 11th Generation chips (without unlocked modifiers for overclocking), as well as slightly cheaper (in theory!) "F" variants with the integrated graphics silicon disabled. If you don't plan to overclock, and do plan to use a video card, it's possible to save some bucks going with a "K," "F," or "KF" variant.

Readers might notice the lack of 11th Generation Core i3 chips this time around, but budget-minded users won't be left in the cold. Though we're here to talk about 11th Generation/Rocket Lake today, 10th Generation Comet Lake desktop isn't done just yet, making a reappearance this time in what is dubbed the "Comet Lake Refresh" family...

There isn't a whole lot on offer here, aside from a 100MHz bump to the base and boost clock of all Core i3 models in the stack, along with compatibility with Z590, H570, and B560 motherboards. But the distinction here is that the Comet Lake Refresh chips are based on the same lithography and architecture as Comet Lake, while Rocket Lake employs some new aspects in both areas.

Next is platform compatibility. While Rocket Lake remains compatible with the LGA 1200 socket first introduced with Intel's 10th Generation/Comet Lake platform, it introduces a new Z590 chipset (and lower-cost, lesser-featured 500-series chipsets) into the mix for the ultra-enthusiast who wants to stay at or just over that mystical "bleeding edge." That said, 11th Generation Rocket Lake chips will be compatible with select Z490 boards, as well. However, the number of Rocket Lake CPUs that will work is limited, as is the number of boards that will support them. (Check with the motherboard manufacturer on the compatibility and BIOS status before you buy, if you're looking to drop a Rocket Lake chip into a 400-series motherboard.)

Now, if Z590 were based on a different socket from Z490, or sported technical or feature upgrades from Intel's last generation of chips, a full chipset refresh like this would be understandable. But there simply isn't a whole host of significant changes on offer here.

The benefits of upgrading from Z490 to Z590 include more PCI Express lanes (eight, to be exact) and native support for PCI Express 4.0. (Some Z490 boards were advertised as "PCI Express 4.0 ready" and will need support for the feature patched in via the BIOS.) Also new with the Z590 chipset: potentially faster USB connectivity with support for Gen 3.2 Gen 2x2, as well as native support for four more USB Gen 3.2 Gen 2 ports than Z490 (now up to 10, versus up to six). Finally, Z590 motherboards will support the option for Wi-Fi 6E. (Read more about that upgrade in our explainer here.)

But that's about it. If those minimal gains in specific areas don't mean much to you, a Z490 board with a 10th Generation Intel chip might well run cheaper than a full upgrade to 11th Generation and Z590. Note that Intel will also support Rocket Lake in boards built off the H470 chipset, but that's where last-gen-chipset support will end. Speaking of which...

Let's Talk About Your Motherboards

This review process, like with the Core i9-10900K review last year, did not go off without a hitch. Though it's now an open secret because of the early sales of the Core i7-11700K, up to today's review embargo date, reviewers (that includes myself, colleagues I've spoken to, and some usual-suspect members of the review network across the web) have noted some issues with the motherboards that were either sent directly by Intel or purchased when they went on sale early last month.

In PCMag's case, the Asus ROG Maximus XIII Hero we received as a part of the press kit took hours of troubleshooting just to get it to a point where it would post in the BIOS after the system was built. From there, another handful of hours were tacked on to get our Windows 10 test environment to stay alive for more than 25 seconds. 

After much tweaking, and a process of elimination longer than my arm, I was finally able to get the motherboard to post using a brand-new beta BIOS (version 0620, published March 23, 2021, for any eventual Hero owners out there). Once we were booting into the OS, this was just the start of our issues. Sure, we were now in Windows 10, but getting the CPU to stay stable in heavy gaming or CPU tests took further tweaks and iterations.

We started our testing with the same settings we've used in previous reviews of Intel CPUs (these include everything from the Core i3-10100 all the way up to the Core i9-10900K), as well as the same XMP II performance profile on our motherboard that we've used to bench all graphics cards released over the past 10 months with the 10th Generation Core i9-10900K. This profile would consistently crash on the Core i9-11900K; however, the Intel Core i5-11600K, as well as the Core i9-10900K, both powered through the benchmarks on the standard XMP II profile without issue.

Ultimately, our testbed would push through our Core i9-11900K benchmarks only if the memory was running at just 3,000MHz (the G.Skill TridentZ sticks we use are rated for up to 3,600MHz), SVID Behavior was tuned all the way down to Intel's recommended Fail Safe profile, and every case fan, radiator fan, and pump was cranked to the fastest profile available on the board.

The Intel Core i9-11900K, like the Core i9-10900K and many other Core i9 and unlocked "K" versions of Intel chips before it, comes with no bundled cooler in the box. This is likely because, to run the chip, Intel recommends at least a 240mm liquid-cooled radiator to keep your processor below ideal temperatures. So you'll need to supply your own cooler at added expense, and suited to the case you'll mount it in.

For what it's worth, AMD also recommends that you use a liquid cooler on its top-end chips like the Ryzen 9 5900X and the Ryzen 9 5950X. However, competing eight-core alternatives to the Core i9-11900K, such as the Ryzen 7 5800X, are efficient enough to run stable on a powerful air cooler at stock settings, if need be.

Testing the Core i9-11900K: Single-Threaded Speed, Multicore Maladies

We tested the Core i9-11900K on an Asus ROG Maximus XIII Hero (Wi-Fi) Z590 motherboard, with 16GB of G.Skill memory clocked to 3,000MHz (for comparability with our earlier CPU reviews), and a Mushkin Pilot-E PCI Express 3.0 boot SSD paired with a Samsung SSD 860 QVO SATA secondary drive.

All this was packed in ADATA's XPG Invader chassis, fitted with a Deepcool GamerStorm Captain 240 EX 240mm liquid cooler, and an MSI 850-watt MPG A850GF power supply. For our gaming tests, we used an Nvidia GeForce RTX 2080 Ti, at Founders Edition clocks, as we have on all recent mainstream and high-end CPU reviews.

We test CPUs using a variety of synthetic benchmarks that offer proprietary scores, as well as real-world tests using consumer apps such as 7-Zip, and AAA 3D games such as Far Cry 5.

CPU-Centric Tests

Out of the gate, we'll make it easy for you: Don't spend a load of time comparing the eight-core Core i9-11900K with the 12-core Ryzen 9 5900X, even though their suggested selling prices are very close to one another.

Why? In nearly every benchmark, save for a win in our legacy-minded iTunes test (not optimized for multiple cores and threads) and our single-core POV-Ray test, the Ryzen 9 5900X is categorically a faster pick while also producing less heat with lower power requirements. If you're stuck between the two, simply stop reading here and grab yourself a Ryzen 9 5900X (if you can find one, of course). 

That said, the Ryzen 9 5900X also had the privilege, when we tested it, of running on a mature motherboard platform that behaved exactly within expectations straight out of the box. Despite some driver stumbles with Ryzen launches in the past, the Ryzen 5000 Series was comparatively painless versus what we had to do to get the Core i9-11900K to work on our testbed within proper limits.

The more interesting numbers are the ones we can't see. We didn't get an advance sample of the eight-core/16-thread Core i7-11700K ($399 suggested price) when it went on (premature!) sale earlier this month, nor were we sent one as a part of our press kit. We did, however, get some time with one in the MSI Aegis RS desktop that was sent to us for review (a prebuilt system), and it regularly beat out the Core i9-11900K in multicore tests, but trailed in single-core. (We haven't charted the Core i7-11700K in here because it was run on this different, retail system with slightly different settings.)

Though there are differences in the builds (for one, the MSI desktop we tested worked out of the box with no tweaking), in our eyes this makes the case, however preliminary, for the Core i7-11700K as a likely better value-for-money eight-core option to consider at launch in Intel's high-end Rocket Lake lineup.

Finally, if you don't mind going back one generation, the Comet Lake-based Core i9-10900K (with the help of our now-rock-steady Z490-based Asus ROG Maximus XII Hero Wi-Fi motherboard) posted substantially better results in multicore runs than what we saw during our runs of the 11900K. Of course, the 10900K is a 10-core/20-thread chip, so in highly threaded tasks, no amount of boost tweaking and thermal optimizing on Intel's part with the 11900K could pick up the slack in tasks when all the cores and threads are engaged. No matter which way you swing the Core i9-11900K bat, there's almost always another more cost-conscious processor to choose from, Intel or AMD.

Gaming at the High End: Intel Core i9-11900K Frame Rates With Discrete GPU

Here's what we saw in our bank of gaming tests with our GeForce RTX 2080 Ti card running the show. This top-end consumer graphics card is the primary arbiter of performance at 4K with all of the CPUs that we have laid out below. At 1080p, though, the card gets out of the way a bit more and lets the CPU differences shine. (We test with 3DMark Fire Strike Ultra and seven games.)

Now, this is the first time in a long time that Intel has released a top-end processor that isn't the de facto gaming king straight out of the box. The Intel Core i9-9900K, the Core i9-9900KS, and the Core i9-10900K all set records across the board when they were released, especially in multi-threading-friendly games like Rainbow Six: Siege and Counter-Strike: Global Offensive.

But now that AMD has seriously upped its gaming chops with its Ryzen 5000 Series, Intel has some close company at the top of the charts. Though it makes a solid showing in most 1080p tests here, the 14nm Intel Core i9-11900K struggled in spots to keep pace with its 7nm competition from the likes of the Ryzen 7 5800X, the Ryzen 5 5600X, and even the Ryzen 3 3300X in limited 4K resolution runs where the GPU is doing all the heavy lifting.

The Core i9-11900K takes an outright frame-rate victory in our 4K run of Rise of the Tomb Raider (84fps, moving the marker up by one), while also hitting new highs in both resolutions of our legacy run of Hitman: Absolution.

Again, I should stress that this lack of total dominance may well be a byproduct of our power limitations put on the chip, which themselves were a necessity for basic operating system stability on the Core i9-11900K, let alone stability in a benchmark like Rise of the Tomb Raider. But even with what we saw, esports pros and users of high-refresh monitors won't find themselves disappointed much here, if at all. This rivalry in frame rates is a literal game of millimeters now, not even inches.

A Look at Overclocking and Thermals

In our attempts to push the Intel Core i9-11900K to its thermal limits in a 10-minute stress test in CoreTemp, we found no issues getting the CPU to post a maximum temperature of 96 degrees C in our testing, but beyond that the system crashed. On our next attempt, with stricter thermal limits in place, the temperatures were closer to reasonable, but still on the high end, peaking at 88 degrees C.

In that profile, the Cinebench score was roughly 15% slower than the results we saw in the profile we used to benchmark. Again, we can't say for certain if this is because we're right on the limit of Intel's recommended cooling solution (a 240mm liquid cooler), or it's down to Asus' pre-tuning of the motherboard.

Either way, once you look at the AMD Ryzen 9 5900X and its 12 cores that top out at just 83 degrees C in the same 10-minute run, it gets a little harder to give Intel the benefit of the doubt on this one. We know 14nm, pushed to the outer limits, is going to run hot. That's no surprise, but just how hot it runs this time around is a bit concerning. Don't skimp on the recommended cooler, is all we can say.

Last, on the subject of overclocking, given that we couldn't get the Intel Core i9-11900K to post into Windows 10 using the stock motherboard profile, hitting a stable overclock profile was pretty quickly stricken off the list of options. Sure, I tried to overclock it, but I also sat there and watched the BIOS cycle itself through after I applied even a 50MHz boost to the CPU's clock speed using either the BIOS or Intel's own Extreme Tuning Utility. No dice in the early going.

As we get more familiar with the issues of 11th Generation CPUs, and more BIOS updates are pushed post-launch, we'll circle back to overclocking to see if the chip can handle a more sizable boost later on.

Verdict: Stay Tuned...But It Might Be a Rerun, Anyway

At the time of this review, we determined that the anomalous results we saw in our experience testing Intel's Core i9-11900K in PC Labs are down to a one-two punch. (Note the italic emphasis; your mileage may vary when you drive this chip, and on what motherboard.) 

First is the BIOS stumble we had. While we were eventually able to wrangle it to a point where the chip wouldn't outright crash during testing, the only way to prevent the BIOS from pushing the Core i9-11900K over the edge was to enforce a few restrictions on the memory speed, the thermal limits, and the power budget. This prevents the numbers that we've gathered from serving as a perfect 1:1 comparison for other CPUs we've tested before it, seeing as how the current bank of Comet Lake numbers we have were all tested on a Z490 Asus ROG Maximus XII Hero motherboard, utilizing the onboard XMP II profile with all 16GB of our DDR4-3600MHz memory running at 3,000MHz. 

Second are the limitations of our CPU cooler. When I asked Intel about recommended cooling during the initial press briefing for Rocket Lake during CES, the company said it recommended a 240mm liquid cooler as the minimum for what the Core i9-11900K would need to run comfortably. And while we have a 240mm AIO cooler installed, for the sake of this review we'll assume that either a 280mm or 360mm cooler might have, at least in some way, helped to close the gap in multicore performance between the Core i9-11900K in our testbed and the performance of the Core i7-11700K in our MSI Aegis RS desktop.

Which brings us to the final issue: Who needs these chips? To be sure, there is a pool of Intel die-hards who have been waiting for PCI Express 4.0 to come to the platform and have potential peak I/O performance come up to parity with AMD. But for the rest, a Z490 board with a Core i9-10900K and a BIOS update will do the job just as well (on the same 240mm cooler, no less). 

Now, we want to be fair to Rocket Lake and recognize that it is early days for the platform. We tested the Core i9-11900K sample we were shipped with an Intel-provided motherboard, first running on an early BIOS that was distributed to the press and then, when problems ensued, patched to the latest version from Asus. Does this mean your experience will be identical to ours? Hopefully not! This is the second straight Intel flagship CPU launch in which the motherboard drivers were volatile, and pre-launch problems aren't unusual for either brand.

In 2020, we ran into issues with boost clocks when originally testing the 10th Generation Core i9-10900K on early BIOSes on the Z490 version of the Asus Hero. But since then it's become our bedrock testbed, used for testing dozens of graphics cards and Intel-based CPUs, and several hit record highs throughout the course of 2020.

So it stands to reason, then, that the same kinks could soon get shaken out of 11th Generation Core. Right now, things are a bit wobbly, but not so much so that you can't see Intel's intention underneath it all. If the company can work with motherboard manufacturers to tune the out-of-the-box BIOS profiles to better suit the thermal and TDP limits of the Core i9-11900K, the CPU will likely become a solid-enough upgrade on an already solid-enough platform.

"Solid enough," though: That's the highest honor we can see it achieving, in a best-case scenario. The Core i9-11900K, as we've been able to test it, isn't a processor we'd recommend buying right out of the gate. You can get very close performance (and in some cases—ahem, multi-threading!—better performance) from a Core i9-10900K, a chip that will slot just fine into select Z590 motherboards, if getting onto the latest platform is the deal-breaker in your upgrade-decision process. Even the Core i9-9900K remains a solid choice at this price point, if you can find one and happen to own a supporting LGA 1151 motherboard.

But all of them, ultimately, are still overshadowed by AMD's Ryzens. If AMD's 3000 Series of desktop CPUs was a base hit, then the 5000 Series was a home run. The two remaining strongholds for Intel—single-threaded performance, and gaming performance—were, on a cost-to-performance ratio, breached in places by AMD in our benchmarks, though admittedly not by so much as to put Intel completely out of the race.

In sum, the strength of AMD's latest Ryzen 7 and 9 5000 Series chips is impossible to ignore. In Intel's defense, the AMD Ryzen 7 5800X is a spectacular eight-core processor, one of the best we've ever seen, and to hit (or even come close to hitting) that bar on an aged-out lithography would be something special on Intel's part. That will have to wait, perhaps, for 12th Generation Core. Can't get mad at the magician for just performing tricks, instead of real magic, can we?