The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Intel’s Kaby Lake-X announcement in May 2017 added two four-core processors—the Core i7-7740X and Core i5-7640X—to its high-end desktop Core X family. Both use the X299 chipset and LGA2066 socket, but they are not higher-core-count CPUs than the mainstream Kaby Lake chips of the same era. Their main distinction was bringing K-series-style, unlocked desktop parts to Intel’s larger X299 platform.
What Intel announced
The Kaby Lake-X launch comprised two models, both recorded by Intel as launching in the second quarter of 2017: the four-core/eight-thread Core i7-7740X and the four-core/four-thread Core i5-7640X. Intel lists both on its X299 compatible-products page, while its historical specifications are in the Products formerly Kaby Lake database.
Unlike mainstream Kaby Lake desktop processors, the X models have no integrated graphics and require a discrete GPU. They were designed for builders who wanted the X299/LGA2066 platform and its high-end-desktop expansion options while staying with four-core Kaby Lake microarchitecture.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Core i7-7740X vs. Core i5-7640X
| Processor | Cores / threads | Base / maximum turbo | Cache | TDP | Platform |
|---|---|---|---|---|---|
| Core i7-7740X | 4 / 8 | 4.30 / 4.50 GHz | 8 MB | 112 W | X299 / LGA2066 |
| Core i5-7640X | 4 / 4 | 4.00 / 4.20 GHz | 6 MB | 112 W | X299 / LGA2066 |
The i7-7740X adds Hyper-Threading, higher frequencies and 2 MB more cache than the i5-7640X. Both carry a 112 W thermal design power rating. Intel’s database and AnandTech’s 2017 launch comparison report these launch-era specifications; they are not modern benchmark results or current buying-performance claims. AnandTech’s comparison also records DDR4-2666 support for the X parts and integrated HD 620 graphics on the corresponding mainstream K-series comparison CPUs, but no integrated graphics on Kaby Lake-X: AnandTech’s launch coverage.
#1 Best Overall
- 4 Cores / 8 Threads
- 3.60 GHz up to 4.20 GHz Max Turbo Frequency / 8 MB Cache. Sockets Supported: FCLGA1151, Max Memory Size: 64 GB, Memory Types: DDR4-2133/2400, DDR3L-1333/1600 at 1.35V
- Compatible only with Motherboards based on Intel 100 or 200 Series Chipsets
- Intel Optane Memory Supported
- Intel UHD Graphics 630
Why put four-core CPUs on X299?
X299 was Intel’s high-end desktop platform, intended for a broader Core X range that extended from four to 10 cores in the 2017 launch generation. Kaby Lake-X offered an entry point into that platform with unlocked multipliers and high clock speeds, but the processors themselves did not provide the additional cores associated with higher-end Core X models.
- Platform choice: LGA2066 and X299 rather than the mainstream LGA1151 desktop platform.
- Graphics requirement: a separate graphics card is mandatory because neither chip includes an iGPU.
- Power and cooling: the 112 W rating is higher than the 2017 mainstream K-series comparison parts, so the motherboard power design and cooler matter.
- Total cost: an X299 board and discrete graphics card can make a Kaby Lake-X system substantially different from a mainstream Kaby Lake build, even when CPU core counts are similar.
Availability was historical, not a current-stock guarantee
In an August 2017 announcement, Intel wrote: “The 4- to 10-core Intel® Core™ X-series processors are already on shelves and available at multiple retailers, along with more than 200 Intel X299 Chipset motherboards.” That statement describes availability at the time and does not establish present-day inventory, pricing or value. The i7-7740X and i5-7640X are 2017-era parts, so any current listing should be treated as used, old stock or marketplace inventory until verified.
Rank #2
- Game Without Compromise. Play harder and work smarter with Intel Core 14th Gen processors
- 20 cores (8 P-cores plus 12 E-cores) and 28 threads. Integrated Intel UHD Graphics 770 included
- Up to 5.6 GHz with Turbo Boost Max Technology 3.0 gives you smooth game play, high frame rates, and rapid responsiveness
- Compatible with Intel 600-series (with potential BIOS update) or 700-series chipset-based motherboards
- DDR4 and DDR5 platform support cuts your load times and gives you the space to run the most demanding games
X299 compatibility and the BIOS trap
Intel’s chipset list confirms platform compatibility at the chipset level, not guaranteed operation on every board revision. Motherboard manufacturers control firmware support, so check the exact model’s CPU-support list and BIOS notes before buying a processor or board.
There is an additional one-way compatibility issue. Intel’s support guidance says that BIOS updates adding support for the listed 10th-generation Core X processors—Core i9-10980XE, i9-10940X, i9-10920X and i9-10900X—remove compatibility with the Core i5-7640X and Core i7-7740X. Read the board maker’s instructions and Intel’s Required BIOS Updates and Frequently Asked Questions Related to Intel Core X-series Processors before flashing firmware. Do not assume that rolling back is supported; follow the manufacturer’s documented procedure.
Rank #3
- Game Without Compromise. Play harder and work smarter with Intel Core 14th Gen processors
- 20 cores (8 P-cores plus 12 E-cores) and 28 threads. Discrete graphics required
- Up to 5.6 GHz with Turbo Boost Max Technology 3.0 gives you smooth game play, high frame rates, and rapid responsiveness
- Compatible with Intel 600-series (with potential BIOS update) or 700-series chipset-based motherboards
- DDR4 and DDR5 platform support cuts your load times and gives you the space to run the most demanding games
How to evaluate one for an existing system
- Identify the motherboard’s exact model and hardware revision.
- Check the manufacturer’s CPU-support page for the i7-7740X or i5-7640X and the required BIOS version.
- Read later BIOS release notes for any statement that 10th-generation Core X support removes Kaby Lake-X support.
- Confirm that the system has a discrete graphics card, suitable cooling and power delivery for a 112 W processor.
- Compare the complete platform cost and condition with other compatible used CPUs; the sources do not establish current prices or stock.
What the announcement did—and did not—change
Kaby Lake-X brought Intel’s latest 2017 mainstream microarchitecture into the Core X branding and X299 ecosystem. It did not make the i7-7740X or i5-7640X multi-core equivalents of Intel’s larger Core X chips, nor did it include integrated graphics. The practical decision was therefore about platform features, expansion and an existing X299 system—not a simple assumption that “high-end desktop” meant more CPU cores.
Quick Recap
Rank #4
- Model: Intel Core i7 Processor i7-3770
- Clock Speed: 3.4 GHz
- Max Turbo Frequency: 3.9 GHz
- DMI: 5 GT/s
- Intel Smart Cache: 8 MB
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
