Introduction

Today, we have with us the Intel Core i9-10900 10-core processor. We've reviewed nearly every other Comet Lake 10th Gen Intel Core processor, and this part eluded us because supply for the Core i9-10900 was incredibly low until last week. Our reviews of the non-K Core i5 and Core i7 series show that opting for a non-K (multiplier-locked) SKU makes sense for those who just want the core counts on offer for a particular Intel Core brand extension as they are unwilling to hunt for the relatively small single-digit percentage performance gains to be had with manual overclocking. Don't forget to check out our review of the Core i9-10900K for reference. In this Core i9-10900 review, we're looking at Intel's 10-core/20-thread processor, which is priced at $440, or a straight $60–$70 saving over the i9-10900K. There's also an in-box cooler for those who want to economize on their build and add aftermarket CPU cooling later.

The "Comet Lake" microarchitecture on which the i9-10900 is based is possibly the final implementation of the "Skylake" core design Intel has been monetizing since 2016, using the same 14 nanometer silicon fabrication process. Facing severe competition from AMD and its Ryzen family of processors, Intel has for the past three Core generations stepped up core/thread counts across the board. This is because AMD began catching up on IPC, which meant the only way Intel could compete is by increasing core counts and clock speeds. Compared to the previous generation, which offered 8-core/16-thread processors as "i9", the 10th Gen Core i9 now has 10 cores and 20 threads.



At $440, the Core i9-10900 is spaced barely $30 apart from the i7-10700K, which has two fewer cores, but an unlocked multiplier. The i9-10900 is a 10-core/20-thread Socket LGA1200 processor clocked at 2.80 GHz base, with up to 5.20 GHz maximum boost frequency. As a Core i9 part, Intel enabled not just Turbo Boost 2.0 and Turbo Boost Max 3.0 (TBM3), but also its new Thermal Velocity Boost (TVB) algorithm, which opportunistically boosts the processor up to 5.20 GHz, beyond its 5.10 GHz TBM3 frequency, depending on the effectiveness of your cooling solution.

As we'll confirm throughout our Core i9-10900 review, the CPU has a glaring Achilles heel: its TDP of just 65 W. While low TDP is never a bad thing per se for a 10-core "Skylake" 14 nm chip, this results in a PL1 (power limit 1) of just 65 W to sustain elevated clock speeds, with an increased PL2 of 224 W for tiny bursts of TVB frequency, and the integrated graphics will consume power, too, if used. Luckily, with its 10th Gen Core processor series and Z490 chipset, Intel has given motherboard designers greater freedom to override power limits, many of whom have passed these tuning abilities on to end users. In our review of the i7-10700, we observed that when unshackled from stock power limits, a significant amount of performance can be unlocked, which sometimes even exceeds the stock performance of the unlocked "K" part.

In this review, we put the Core i9-10900 through its paces to explore just how fast this chip is out of the box, how much performance can be squeezed out of it even without the unlocked multiplier, and whether you could potentially save yourself $60 by opting for this chip over the i9-10900K. We offer four data points for the Core i9-10900 in this review. The first data point (green bar) is the processor as it works out of the box, completely stock, with Intel power limits active, but 3200CL14 memory. The second data point (orange) is when this stock processor is paired with the DDR4-2666 memory clock mandated by cheaper non-Z490 motherboard. The third data point (blue) explores a "max turbo" scenario where the power limits are removed completely in the BIOS. The last data point (red) explores the fastest possible manual overclock for this chip, achieved with maximum power limits and a BCLK of 103 MHz (beyond which Intel processors are designed to fail).

A Closer Look

Our Core i9-10900 sample came in a tray-only package. The retail packaging includes a 95 W TDP-capable heatsink, which will help keep overall system cost down.


The Core i9-10900 looks like any LGA1xxx processor released by Intel in the past decade. The processor is only compatible with Socket LGA1200 motherboards because the position of the round notches has been changed. It will not work with an older motherboard.


Luckily, Socket LGA1200 retains cooler compatibility with all older LGA115x-series sockets. This means you're going to be spoiled for choice when picking a cooler to go with this processor.

Architecture

Under the hood of the Core i9-10900 is the 10-core "Comet Lake-S" silicon built on the same 14 nm++ process as the previous two generations, but with a key difference.


Intel physically thinned the die along the Z-axis by removing as much of the silicon bulk as possible, with the idea being that heat generated by the die travels through less silicon. The more conductive copper integrated heatspreader has been made thicker, and a solder thermal interface material (STIM) is used between the two. The die area is estimated by AnandTech to be around 198.4 mm², and from the looks of it, Intel can't add any more cores on this package by stretching the die without chopping off the iGPU.


The "Comet Lake-S" silicon is laid out similar to the past four generations of Intel mainstream processors, with two rows of CPU cores flanked by the iGPU on one side and the system agent (integrated northbridge) on the other, and a Ringbus Interconnect serving as town square between the various components. The last-level cache is scattered across as slices, adding up to 20 MB of unified L3 cache all cores can access equally.

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. The iGPU solution, although present on the silicon, is permanently disabled by Intel. 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. All SKUs in the desktop 10th Gen processor series appear to have the top GT2 trim. 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.


The core itself is identical in design to "Skylake," and there are hence no IPC increases to be had. As we explained in the introduction, all of Intel's efforts to increase gaming, single-threaded, and less-parallelized application performance revolve around increasing clock speeds and deploying as many as three intelligent boosting algorithms to achieve the advertised clock speeds.

Boost Algorithms

The Core i9-10900 has a nameplate base frequency (aka nominal clock) of 2.80 GHz. The processor embarks on a fascinating journey toward 5.20 GHz from here. The processor leverages Turbo Boost 2.0 to raise clock speeds up to 5.00 GHz, with varying boost multipliers along the way to workloads scaling across multiple cores. Beyond this, the Turbo Boost Max 3.0 algorithm, carried over from the company's Core X HEDT processors, is engaged. The algorithm raises frequencies of the processor's two favored cores up to 5.10 GHz. Beyond this, the processor invokes Thermal Velocity Boost, a brand-new algorithm that opportunistically overclocks the processor to 5.20 GHz in short bursts provided the processor's cooling solution is effective (able to keep temperatures below 70°C), and the processor's power budget permitting.

With "Comet Lake," Intel is introducing favored cores to its mainstream desktop processor segment, which was until now restricted to its HEDT and server processors. AMD supports this tech across its Zen product stack. Two of the best-performing cores on the silicon are identified at the time of each die's manufacturing, their information is hardcoded. Favored cores-aware operating systems (Windows 1709 or later and Linux kernels since January 2018) are able to identify this information, and send the most traffic to these two cores as they are able to sustain boost frequencies the best.

PL1, or power level one, spreads a 65 W power budget to support them across a default 28-second Tau (a time value for which the processor is allowed to sustain its boost frequencies before having to fall back to nominal clocks). PL2, on the other hand, is something else. Set at 224 W, motherboard manufacturers have been given the freedom to override PL2 and Tau as they see fit, so various motherboards implement power limits differently depending on the effectiveness of their VRM solution. You are hence rewarded for buying a pricier motherboard that has a better VRM coupled with a more aggressive vendor-supplied power management. Of course, all boards come with Intel-spec fallbacks. We will examine the boosting behavior at Intel spec and compare it with the "ASUS enhanced" specs of the ROG Maximus XII Extreme later on in this review.

Intel introduced a handful of overclocker-friendly features with the 10th generation, including the ability to toggle HyperThreading on a per-core basis rather than globally. This could be an interesting option for those gaming and streaming, where a certain number of cores have HTT disabled for the best gaming performance and certain cores have them enabled, with Windows process core affinity settings taking care of the rest.

The company also introduced the ability to overclock the DMI chipset bus. DMI is a PCIe-based interconnect that handles transfers between the processor and the chipset (PCH). The LGA1200 platform uses DMI 3.0 (comparable to PCI-Express 3.0 x4 in terms of bandwidth). Intel has apparently decoupled PCIe clock domains to enable you to overclock the DMI and PEG (that topmost x16 PCIe slot) without destabilizing your PCIe setup for graphics cards. Multiplier-based overclocking, however, isn't possible on the Core i9-10900.

The Z490, H470, and B460 Platforms

Z490 is the top 400-series chipset targeted at gaming desktops and PC enthusiasts, as it enables serious overclocking and multi-GPU support. In terms of I/O capabilities, the chipset is nearly identical to the Z390, with 24 downstream PCIe gen 3.0 lanes, six SATA ports, six USB 3.2 gen 2 ports that can be converted to three USB 3.2 gen 2x2 ports, ten USB 3.2 gen 1 ports, and fourteen USB 2.0 ports. Intel is recommending its i225-V 2.5 Gbps Ethernet chip as the wired networking solution to go with Z490, and the company's AX201 802.11ax WiFi 6 WLAN solution to go with the chipset's CNVio interface.


You are more likely to pair locked Intel Core processors with the B460 or H470 chipsets. B460 has motherboards start at around the $90 mark. It comes with 16 downstream PCIe gen 3.0 lanes (compared to just 12 on the previous-generation B360). Compared to Z490, you get fewer PCIe lanes (16 vs. 24) from the chipset, and fewer USB 3.2 ports (eight 5 Gbps ports and no 10 Gbps ports compared to six 10 Gbps and ten 5 Gbps ports on the Z490). You also lose out on CPU overclocking features and multi-GPU capabilities (such as SLI). B460 motherboards also come with memory frequency restrictions set to DDR4-2933. The H470 is an interesting middle ground between the Z490 and B460. You still lose out on multi-GPU and overclocking, but get more platform PCIe lanes (20 vs. 16 on the B460 and 24 on the Z490), as well as four 10 Gbps USB 3.2 ports in addition to what you get from the B460.

Despite being a multiplier-locked chip, we'd still recommend you check out at least a mid-range Z490 chipset motherboard to benefit from unlocked memory clocks, power limit flexibility, and good enough CPU VRM solutions.