Introduction

Intel today launched its 11th Generation Core “Rocket Lake” desktop processor family led by the Core i9-11900K—this is its long-awaited review. With the Core i9-11900K, Intel wants to respond to the AMD Ryzen 5000 series, which snatched overall performance leadership away from the company. Rocket Lake is Intel’s first attempt at improving per-core (single-threaded) performance in several years, through the introduction of the new “Cypress Cove” CPU core. Intel claims IPC gain over the previous generation of up to 19%. The i9-11900K is an 8-core/16-thread processor, which is a step backward from its 10-core/20-thread predecessor, the i9-10900K, but Intel believes that the IPC gain and enhancements to the multi-core boosting algorithm should help recover some of the multi-threaded performance despite the two-core deficit. This is also their attempted hint at the market and software developers that eight cores should be plenty for cutting-edge gaming and client desktop tasks.

The reason Intel had to stop at eight cores for Rocket Lake has more to do with the fact that the processor is still manufactured on the 14 nm silicon fabrication node Intel has been lugging along for six years now. The Core i9-11900K is built on the same Socket LGA1200 package as its predecessor, and the package is physically of the same size as the i7-860 from 2009. The new Cypress Cove CPU cores are significantly larger than the “Skylake” cores on “Comet Lake,” and the new Gen12 Xe LP iGPU is larger than the Gen 9.5 unit, too. As a result, elongating the die to cram in more cores wasn’t an option. Add to this that the 14 nm node limits the power budget, and the 10-core Comet Lake was already flirting with 250 W package power draw. Physically removing the iGPU to make room for the extra two cores wasn’t an option either, as Intel emphasizes the iGPU to sell these chips to the vast majority of desktop users that don’t need discrete graphics. Intel plans to significantly change its mainstream desktop socket with the future generation “Alder Lake,” however.

Why Intel stuck with 14 nm is another mystery. Intel’s position is that to accomplish the performance target of Rocket Lake on the desktop platform, 14 nm was sufficient. Intel already has a more advanced silicon fabrication node, the 10 nm SuperFin, which it’s using to make 11th Gen “Tiger Lake-U” mobile processors with plans to launch a new 8-core “Tiger Lake-H” mobile chip later this year. Mobile processors make up a major share of Intel’s client CPU sales, and with the recent surge in notebook sales, the company wants to maximize its 10 nm foundry utilization for mobile chips. The desktop platform has a relatively “unlimited” power budget compared to mobile, and with 10th Gen “Comet Lake-S,” Intel seems to have decided that it’s willing to take the heat for selling a hot and inefficient desktop chip as long as it’s competitive.

We’ll go into the nuts and bolts of Rocket Lake on the following pages, but put briefly, the chip combines eight new Cypress Cove CPU cores with a Gen12 Xe LP integrated graphics core and an updated platform I/O that includes PCI-Express Gen 4. The chip also puts out eight more PCIe lanes than the previous generation. These contribute to a CPU-attached NVMe interface, much like those of AMD Ryzen chips, and a double-width DMI x8 chipset-bus. The general purpose PCIe connectivity put out by the new Intel 500-series chipsets continues to be PCIe Gen 3.

With this generation, Intel has an ace up its sleeve—DLBoost, or hardware acceleration of AI deep-learning neural net building and training. Intel claims DLBoost accelerates DNN training performance by up to six times compared to normal x86 execution. DLBoost made its debut with the company’s 10th Gen “Ice Lake” mobile processors, and Intel sees huge potential for AI in several client-relevant media tasks, such as quick image and video manipulation—just like on the latest smartphones. The company also put out plenty of developer documentation and is working with ISVs to promote DLBoost. Another feature making its desktop debut is the new AVX-512 instruction set, or at least a truncated version of it, with only client-relevant instructions.

The Core i9-11900K 8-core processor is clocked at 3.50 GHz, with a maximum Turbo frequency of 5.30 GHz using Thermal Velocity Boost and an all-core boost frequency of 4.70 GHz. Each of the eight Cypress Cove cores comes with 512 KB of dedicated L2 cache, and the chip has 16 MB of shared L3 cache. The i9-11900K is unlocked and ready for overclocking. Intel has introduced several new features for overclockers, which we’ll detail on the following pages. The i9-11900K is priced at US$539 in 1,000-unit tray quantities, which should put its retail starting price at around $550, the same pricing territory as AMD’s 12-core Ryzen 9 5900X. In this review, we put the Core i9-11900K through an exhaustive new set of CPU and gaming tests to show you if Intel has managed to take back the crown from AMD.