Intel Core i7-7740X Kaby Lake-X Review

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Test Setup

Test Systems

We're using the MSI X299 Gaming Pro Carbon AC for testing. We disabled the all-core Turbo Boost feature to ensure a level playing field.

There were several demonstrations of memory overclocking beyond DDR4-4000 with Kaby Lake-X processors at Computex, but we settled on DDR4-3200 for our overclocked config to match the memory data transfer rates of our Ryzen models.

We introduced our new test system and methodology in How We Test Graphics Cards. If you'd like more detail about our general approach, check that piece out.

The only updated components in our German lab are the CPU, system memory, motherboard, and new cooling solution, so we'll just provide a quick overview in the following table:

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Test Equipment and Environment
SystemGermany Intel LGA 2066Intel Core i9-7900X, i7-7740X Core i7 7740X, Core i5-7640X Core i7 7740X, Core i5-7640XMSI X299 Gaming Pro Carbon AC4x 4GB G.Skill Ripjaws 4 DDR4-2600AMD Socket AM4 WorkstationAMD Ryzen 7 1800X, 1700X, 1600X, 1500XMSI X370 Tomahawk2x 8GB G.Skill Ripjaws V DDR4-3200Intel LGA 2011v3Intel Core i7-6900KMSI X99S XPower Gaming Titanium4x 4GB Crucial Ballistix DDR4-2400Intel LGA 1151Intel Core i7-7700K, i5-7600KMSI Z270 Gaming 72x 8GB Corsair Vengeance DDR4-3200 @2400 MT/sAll SystemsGeForce GTX 1080 Founders Edition (Gaming)Nvidia Quadro P6000 (Workstation)1x 1TB Toshiba OCZ RD400 (M.2, System)2x 960GB Toshiba OCZ TR150 (Storage, Images)Be Quiet Dark Power Pro 11, 850W Power Supply Unit (PSU)Windows 10 Pro (All Updates)Be Quiet Dark Power Pro 11, 850W Power Supply Unit (PSU)Windows 10 Pro (Creators Update)U.S.Intel LGA 2066Intel Core i9-7900XMSI X299 Gaming Pro Carbon AC4x 8GB Corsair Vengeance DDR4-2666 @ 2666 and 3200 MT/sIntel LGA 2011v3Intel Core i7-6900K, Core i7-6950XASRock X99 Extreme44x 8GB Corsair Vengeance DDR4-2666 @ 2666 and 3200 MT/sAMD Socket AM4 Workstation AMD Ryzen 7 1800X, 5 1600XMSI X370 Xpower Gaming Titanium 2x G.Skill FlareX DDR4-3200 @ 2666 (stock), and 3200 MT/s Intel LGA 1151 Intel Core i5-7600K, i7-7500 MSI Z270 Gaming M7 2x G.Skill FlareX DDR4-3200 @ 2400 All EVGA GeForce GTX 1080 FE 1TB Samsung PM863 SilverStone ST1500, 1500W Windows 10 Creators Update Version 1703
CoolingGermanyAlphacool Eiszeit 2000 ChillerAlphacool Eisblock XPXThermal Grizzly Kryonaut (For Cooler Switch)USCorsair H115iCorsair H100i v2Arctic MX4
MonitorEizo EV3237-BK (Workstation, Office, HPC)
Power Consumption MeasurementContact-free DC Measurement at PCIe Slot (Using a Riser Card) Contact-free DC Measurement at External Auxiliary Power Supply Cable Direct Voltage Measurement at Power Supply 2x Rohde & Schwarz HMO 3054, 500MHz Digital Multi-Channel Oscilloscope with Storage Function4x Rohde & Schwarz HZO50 Current Probe (1mA - 30A, 100kHz, DC) 4x Rohde & Schwarz HZ355 (10:1 Probes, 500MHz) 1x Rohde & Schwarz HMC 8012 Digital Multimeter with Storage Function
Thermal Measurement1x Optris PI640 80Hz Infrared Camera + PI Connect Real-Time Infrared Monitoring and Recording


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Paul Alcorn
Managing Editor: News and Emerging Tech

Paul Alcorn is the Managing Editor: News and Emerging Tech for Tom's Hardware US. He also writes news and reviews on CPUs, storage, and enterprise hardware.

  • AgentLozen
    I'm glad that the option for Kaby Lake is available on the x299 chipset. In practice it seems impractical. This article shows you have to pay a lot more for slightly higher overclocking potential.

    I'm curious what Intel's plans are for next year regarding their high end desktop chips. They've already used the Kaby Lake X name for this generation. Should we expect Kaby Lake X 8900X?
  • Kaz_2_
    Intel high power consumption is not great in thr long run. You want the best for your investment
  • TJ Hooker
    The curve below shows clearly that waste heat isn't dissipated quickly enough. Just as we did in our AMD Ryzen and Intel Core i9 launch articles, we used a very thin copper plate to measure the heat spreader's temperatures as well.
    Why aren't there any numbers/divisions on the horizontal axis? Also, you say you did the same thing for the Ryzen reviews but I didn't see a similar graph in those articles (might just be blind though).
  • Roland Of Gilead
    in the HPC graph, you have two 'Ryzen 7 1600x' s.....
  • Roland Of Gilead
    power consumption gaming loop - I5 7600x?
  • the nerd 389
    How does the thermal performance of this chip compare to the 7700k? Specifically, does the larger surface area of the heat spreader give you a meaningful increase in thermal conductivity between the die and the heatsink?
  • rantoc
    Dang intel seem to be doing yet another stupid move with X299 beside rushing it out the door making the AMD's pretty brand new architecture/platform appear mature in comparison. As for this move - What's the incentive to pay premium for the X299 when getting a chip like this that won't even utilize it fully? The 7700k and platform are equal in performance in most tests and far cheaper...

    With the poor thermal transfer between the core and heat-spreader the retail chips won't likely even overclock well either. Never cared about the cherry picked "reviews" chips at all when it comes to overclocking as they very rarely represent the retail chips.
  • rantoc
    What's the incentive to buy an expensive motherboard and yet get near zero of it's true potential with this cpu? That's paying for a lot of real estate that can't be used at all and on top of that the same poor thermal transfer between the core and heat-spreader meaning a good stable oc is harder to obtain and far less likely to happen on the retail IE non-review cherry picked ones.

    I think intel shoot themselves in the foot by scaling this one down to much and then couple it with an overpriced platform for what you get out of it, x299 will be good no doubt but only with the right chips and only when the rushed out of door bugs been fixed.
  • This is awesome setup because you can buy x299 motherboard for $219 dollars already which gives you amazing room for later upgrade and this CPU can run 5.0Ghz easily producing very little heat. People at Toms Hardware completely missed the point. I'd rather get $219 x299 motherboard than outdated Z270 for $160.
  • And as for heat...i think heat talk i have been reading lately is just BS.