Introduction

Intel today announced their most exciting processor launch of the year, the Core i9-9900K eight-core based on its 9th generation "Coffee Lake Refresh" silicon. This is exciting because Intel has finally doubled the CPU core counts for its LGA115x mainstream desktop platform after nearly eight years of quad-core products. The company was kicked out of complacency last year by AMD's successful "Zen" architecture announcement, and scampered to create the 6-core 8th generation "Coffee Lake" processor. With AMD maintaining its upward trajectory in performance and value for a second generation, Intel is forced to respond with an increase in core counts for another generation, which we have for review today.

The Core i9-9900K comes at a time when Intel's silicon fabrication foundry advancement has slowed to a crawl and the management running it is in disarray. The company is motivated in not just keeping its customers happy with a "new and improved" product, but also its shareholders. It has become important for Intel to establish a performance leadership over AMD that is indisputable, or at least one that would take AMD long enough to respond to so Intel could get its next-generation foundry on the road, and build future-generation microarchitectures on it. The one at the heart of today's review, the Intel Core i9-9900K, is practically unchanged from the 6th generation "Skylake." Intel dragged the same core design over four generations while focusing on core-count increases and improvements to the 14 nm fabrication process to eek out efficiency.


The star attraction of the review is the new 8-core "Coffee Lake Refresh" silicon, measuring 178 mm² and built on the same 14 nm++ process as last year's "Coffee Lake" 6-core. This chip packs 8 physical cores and 16 MB of L3 cache, which is exactly double the processing muscle as the quad-core "Kaby Lake" silicon from just two years ago. Intel has tweaked its integrated memory controller to support up to 128 GB of memory by adding support for 32 GB memory modules, and deployed certain hardware-level fixes to speculative execution vulnerabilities that dominated headlines for the bulk of the year. This is important because a hardware fix theoretically has less of an impact on performance than a software fix deployed via microcode updates or the operating system.

Intel is using this 8-core die to carve out two distinct SKUs, the Core i9-9900K and Core i7-9700K. The i9-9900K hence isn't exactly a successor of the i7-8700K, but positioned in a new segment above, at around the $500-mark. The Core i9-9900K maxes out the silicon. The i7-9700K, on the other hand, has all 8 cores available, although HyperThreading isn't enabled. The L3 cache amount is also cut down to 12 MB. This part is priced around the $400-mark and succeeds the i7-8700K in both price and performance. Intel hasn't substantially changed its Core i5 lineup, which is still 6-core/6-thread with 9 MB of L3 cache.

Intel is introducing the new Z390 Express chipset with those new processors. This premium chipset is positioned above the Z370 Express and comes with higher CPU VRM requirements to ensure the highest possible overclocking headroom for the new 8-core processors. Also on tap is a newer integrated USB 3.1 controller. It also helps people identify motherboards that are guaranteed to support 9th generation Core processors out of the box. All other Intel 300-series chipsets for LGA1151 client, including H310, B360, H370, and Z370, support these processors, but require BIOS updates.

In this review, we take an Intel Core i9-9900K processor out for a spin through a plethora of productivity, scientific, content-creation, and gaming tests.

A Closer Look

Intel Core i9-9900K is such a special product for Intel that it has given the chip a retail packaging that's found not even on the $1,800 Core i9-7980XE. A large see-through acrylic dodecahedron, which is a 3-D shape with 12 pentagonal faces, greets you at first. Inside is a padded paperboard box, and the processor is packaged inside another tiny acrylic case. That's not all, some retailers pack the outer dodecahedral package into an even bigger paperboard box to prevent scratches or cracks. Your processor is hence hidden inside five layers of packaging!

Unfortunately, the voluminous box is mostly just air. Intel could have very easily gone with a simpler packaging and bundled the processor with a 130 W-capable cooling solution to win over some hearts. AMD is bundling its Wraith Prism with the 2700X. You're either too confident about your processor or overcompensating for asking $500 for a mainstream-desktop processor.


Once you excavate your product out of the packaging, you'll find that it looks like just any other LGA115x-class mainstream desktop processor made in the past nine years. The processor is compatible with LGA1151 motherboards based on the Intel 300-series chipset.


For its mainstream-desktop processors, Intel has maintained a largely uniform package size for the past decade, dating all the way back to Core "Lynnfield" LGA 1156. The cooler mount-hole spacing hasn't changed. You will be spoiled for choice when choosing a compatible cooler; however, make sure it can cope with at least 95 W TDP. Certain low-profile coolers designed for 65 W or 45 W TDP chips are not recommended.

The Coffee Lake Refresh Silicon

At the heart of the Core i9-9900K is the new 8-core "Coffee Lake Refresh" silicon built on the same 14 nm++ process as the 8th generation Core processors. The die is laid out in the same essential design as "Skylake," with two rows of CPU cores sandwiching the ringbus, each core with a dedicated L2 cache and 2 MB slice of the L3 cache. Each core can address the entire 16 MB of L3 cache on the die. For the Core i9-9900K, all L3 cache slices are fully unlocked. For the i7-9700K, each core is configured with a 1.5 MB slice, which adds up to 12 MB. The 6-core i5-9600K is based on a die with only 6 cores physically available, and configured with 1.5 MB slices adding up to 9 MB. Intel is starting to reach the core-count barrier beyond which the ringbus has to be junked in favor of Mesh Interconnect tiles, or it will suffer the detrimental effects of ringbus latencies.


The ringbus is town-square and the primary intra-silicon communications fabric. It binds all eight cores with the uncore components (integrated northbridge, memory controller, PCIe root-complex, etc.) and the iGPU. Intel has improved the integrated memory controller to now support up to 128 GB of dual-channel DDR4 memory. For most users, this is meaningless, but if you plan on building a future-proof machine that will last the next seven years or so, you never know when you'll need more than 64 GB of RAM.


Much of the processor's uncore components are clumped into the System Agent, which contains the memory controller, PCI-Express gen 3.0 root-complex, DMI interface, and memory PHY. On the other end of the ringbus is the Gen 9.5 integrated graphics, which has practically been carried over for the past three generations, featuring 24 execution units in the GT2 trim. At best, Intel may give it some software improvements that leverage the additional CPU power on tap. The iGPU is still branded under Intel's Graphics UHD family. Don't expect to play PUBG at 4K on this; the "UHD" moniker only indicates that the IGP can handle 4K Ultra HD displays, features modern connectivity options such as DP 1.4 and HDMI 2.0, and can playback 4K video in new formats with 10-bpc color and HDR10/Dolby Vision standards.


Between "Skylake" and "Coffee Lake," Intel turned its R&D efforts toward refining the 14 nm process. It met with success on "Kaby Lake," and owing to its significantly higher clock speeds, "Kaby Lake" was able to provide higher performance than "Skylake." With "Coffee Lake," the nominal clock speeds look low, but Turbo Boost frequencies are higher than "Kaby Lake," and refinements in the process allow the chip to sustain elevated boost-clock states better. Between "Coffee Lake" (8th gen) and "Coffee Lake Refresh" (9th gen), the CPU core design has not changed. Intel did implement certain silicon-level fixes against security vulnerabilities.


A long-overdue innovation Intel introduced with the 9th generation is STIM, or soldered thermal interface material, Intel-speak for a soldered IHS (integrated heatspreader). Intel has been using thermal paste as the TIM between the CPU die and IHS for the past several generations, and in response to AMD implementing the soldered IHS across its entire lineup, Intel implemented it on at least the 8-core i9-9900K and i7-9700K. Some of the cheaper parts could continue to use thermal paste.

The Intel Z390 Express Chipset

As we mentioned earlier, the only reason Intel appears to have launched the Z390 Express chipset while its existing Z370 chipset supports this processor through BIOS updates is because there could be motherboards with assured out-of-the-box support for 9th generation Core processors. Intel has also reportedly raised the CPU VRM requirements for the Z390, so motherboards based on it can maximize the overclocking headroom of the i9-9900K and i7-9700K. You can still overclock these chips with Z370. In terms of connectivity, the only thing that sets the Z390 apart from the Z370 is integrated 10 Gbps USB 3.1 and an external WLAN controller for 802.11ac.