Intel Core i7-7740X Kaby Lake-X Review

Final Analysis

Superficially, Intel’s idea to transplant Kaby Lake onto its high-end desktop platform seems like it'd make sense. But ultimately, X299's excessive cost hamstrings Kaby Lake-X. In many ways, the Core i7-7740X reminds us of Intel’s Core i3-7350K. It's a great chip forced into a platform that doesn't match up with its price point.

Core i7-7740X is nearly identical to the existing -7700K; even its price is similar. At stock settings, the -7740X performs a lot like its mainstream counterpart, despite slightly higher base and Turbo Boost frequencies. We noticed the same performance characteristics as -7700K in lightly threaded workloads, such as gaming and most common desktop apps. But the -7740X pales in comparison to the brawnier Skylake-X models in heavy application tests. Lower idle power consumption numbers are likely a result of the -7740X's disabled graphics engine. However, the overall power and thermal measurements come out to be almost the same. Though we still don’t approve of the thermal paste Intel uses between its die and heat spreader, at least closed-loop liquid coolers are fine for this 112W chip.

The “X” in Kaby Lake-X promises extreme overclocking action, and we did eke out a few hundred megahertz over Core i7-7700K. That extra headroom is nice, but it doesn't translate to large gains in our gaming suite. In fact, at stock settings, the -7700K achieved higher average frame rates, while overclocking gave the -7740X a 1.19% advantage. The 99th percentile variances between the chips both fell under 1%, with the advantage going to Core i7-7700K in stock and overclocked configurations. In either case, the difference between these two CPUs is imperceptible, even after overclocking them both. Perhaps that'll improve as X299-based motherboards receive more fine-tuned firmware.

Intel's Core i7-7700K is one of the fastest gaming processors we've ever tested, so matching it is a good thing. But the -7740X doesn't make sense as an equal when we factor in the X299 platform. You are going to pay an extra ~$150 for an X299 motherboard compared to a more mature Z270-based setup, and gain exactly zero features. In fact, you lose the integrated GPU that could be useful for other tasks, such as Ultra HD Blu-ray playback. Dropping the -7740X into LGA 2066 actually disables motherboard features you're paying for like extra DIMM slots, Skylake-X's more robust power delivery, and hamstrung chipset functionality.

Our motherboard contacts have expressed a general reluctance to create Kaby Lake-X-specific motherboards, and unless that changes, there is little reason to jump up to the X299 with a Kaby Lake-X chip. Certain enthusiasts will pursue a stouter overclock from the Kaby Lake architecture, and -7740X delivers in that regard. Intel's pitch is that Core i7-7740X serves as an entry point to X299 that paves the way for upgrades to Skylake-X later. We don't believe there's a big market for an expensive path like that, though. For those with the upgrade itch, either stay with the Z270 and spend bigger on a high-end GPU, or splurge on a true HEDT-class processor.

Intel has its Coffee Lake CPUs coming to market later this year, and we've heard rumors of a six-core model landing on the mainstream desktop. Consider waiting for more information on that prior to going the X299/Kaby Lake-X route, if you're still interested in Core i7-7740X. Also, AMD's Ryzen Threadripper is coming soon. There are just so many reasons not to buy this thing...

Core i7-7740X doesn’t give you anything new. Yes, it's one of the fastest gaming chips ever made, but you can get similar performance from the mature Z270 platform for significantly less money. We appreciate the higher overclocking ceiling, but that doesn't translate into enough benefit to justify the extra investment.

MORE: Best CPUs

MORE: Intel & AMD Processor Hierarchy

MORE: All CPUs Content

This thread is closed for comments
33 comments
    Your comment
  • 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
    Quote:
    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).
  • keith12
    in the HPC graph, you have two 'Ryzen 7 1600x' s.....
  • keith12
    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.
  • AgentLozen
    Quote:
    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.


    I agree that it's cool you have upgrade options when you buy an x299 motherboard. You can spend $350 on Kaby Lake X now then drop another $1000 in the future if you feel the need to buy Skylake X. It seems like Tomshardware didn't give credit to this upgrade path $1350 upgrade path where it's due.

    Some people might just buy Skylake X to begin with and save $350 on Kaby Lake X, but I ask "Why not both?"

    I think you hit the nail on the head on your x299 chipset point. The x270 chipset was obsolete when it launched with Kaby Lake 6 months ago. I'm glad Intel is giving a chance to rectify the situation by giving us access to the x299 chipset. So what if most of the motherboard is disabled because of the architectural differences between Kaby Lake X and Skylake X? What were you going to use those extra PCIe lanes for? Extra professional devices? Psh, whatever.

    Good point about the heat too. I'm tired of people using lines and graphs for stuff. It makes my head hurt. These nerds at Tomshardware could learn a thing or two from our president and just ignore that crap. The heat won't be a problem until you start Windows. That's why you use LINUX!

    Thanks for posting freak777power. We friends <3
  • mossberg
    2164959 said:
    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.


    I would rather take that $60 and get a better graphics card. Why waste this kind of money on a 4c/8t system, when you can get a Ryzen 1700, with 8c/16t, for a similar cost? The R7's are plenty capable at gaming, and are great in workstation type apps. X299 is an overpriced waste of time. I think Linus had it right when he called it a knee jerk reaction.
  • PaulAlcorn
    1636679 said:
    Quote:
    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).


    We've done a LOT of Ryzen reviews, so this might not be the only one that included the test data.

    http://www.tomshardware.com/reviews/amd-ryzen-5-1600x-cpu-review,5014-8.html

    I'll circle back with Igor about the axis.
  • PaulAlcorn
    182540 said:
    in the HPC graph, you have two 'Ryzen 7 1600x' s.....


    Which particular graph? I'm looking over them, but don't see it.
  • PaulAlcorn
    182540 said:
    in the HPC graph, you have two 'Ryzen 7 1600x' s.....


    Which particular graph? I'm looking over them, but don't see it.
  • PaulAlcorn
    2164959 said:
    And as for heat...i think heat talk i have been reading lately is just BS.


    http://www.tomshardware.com/reviews/-intel-skylake-x-overclocking-thermal-issues,5117.html
  • I setup couple machines with x299 with 6 and 8 cores for other people and with 4.2Ghz on 8 Core and 4.5Ghz on 6 Core overclock nowhere to see heat problem. Granted we didn't run Prime but guess what, who plays Prime95 anyway? That unrealistic test will heat up anything you throw at. In other words in everything else i haven't seen 8 core going over 60C at all and idles between 25/30C and entire setup was in Thermaltake X31 with one of the AIO 240mm watercooling kits. I still say, this heat talk is just BS.
  • 496490 said:
    Quote:
    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.
    I agree that it's cool you have upgrade options when you buy an x299 motherboard. You can spend $350 on Kaby Lake X now then drop another $1000 in the future if you feel the need to buy Skylake X. It seems like Tomshardware didn't give credit to this upgrade path $1350 upgrade path where it's due. Some people might just buy Skylake X to begin with and save $350 on Kaby Lake X, but I ask "Why not both?" I think you hit the nail on the head on your x299 chipset point. The x270 chipset was obsolete when it launched with Kaby Lake 6 months ago. I'm glad Intel is giving a chance to rectify the situation by giving us access to the x299 chipset. So what if most of the motherboard is disabled because of the architectural differences between Kaby Lake X and Skylake X? What were you going to use those extra PCIe lanes for? Extra professional devices? Psh, whatever. Good point about the heat too. I'm tired of people using lines and graphs for stuff. It makes my head hurt. These nerds at Tomshardware could learn a thing or two from our president and just ignore that crap. The heat won't be a problem until you start Windows. That's why you use LINUX! Thanks for posting freak777power. We friends <3


    I find your post rather pretty amusing. Extra PCIe lanes get disabled but that's because of number of PCIe quad core carries, nothing there to worry about. Again $219 x299 is way better deal than Z270 giving you hell of more options currently and in the future. I setup couple 6 and 8 core x299 machines and haven't seen any heat or throttling issues. Rule of thumb is don't trust anything you read these days and do your own research and then make conclusion.
  • TJ Hooker
    1920539 said:
    1636679 said:
    Quote:
    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).
    We've done a LOT of Ryzen reviews, so this might not be the only one that included the test data. http://www.tomshardware.com/reviews/amd-ryzen-5-1600x-cpu-review,5014-8.html I'll circle back with Igor about the axis.

    Thanks. If we get the horizontal axis for the graph, we could then look at the slopes of the core temp vs power for Ryzen/Skylake-X/Kaby Lake-X (all using a constant 20C waterblock) as a way to compare the effective thermal resistance of their respective TIM+heatspreader.
  • tuvok
    Good review, now de-lid it and pair with 3600Mhz+ ram and stretch its legs.
  • the nerd 389
    127027 said:
    Good review, now de-lid it and pair with 3600Mhz+ ram and stretch its legs.


    It doesn't make much sense to de-lid the 7740x. It's main advantage is that you can upgrade to Skylake-X without replacing the motherboard. You don't de-lid a CPU if you can't afford the next better CPU (assuming you're not making a more fundamental mistake). Beyond that, the 7740x has marginally higher clock speeds, but that is a moot point if you compare a de-lidded 7740x to a de-lidded 7700k.

    Add the price difference into the mix, and things quickly favor the 7700k. Not including the platform, you'll probably screw up your first one or two attempts at replacing the TIM. That means the 7700k has an advantage of $100-$150 in the CPU alone. Once you account for that motherboard, you're down several hundred dollars if you go with the 7740x.

    For the additional money, you don't really get anything. The additional capabilities of the x299 are totally lost on the 7740x.
  • jimmysmitty
    496490 said:
    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?


    Probably Coffee Lake and/or Cannon Lake X since those are the next upcoming uArchs.
  • abbadon_34
    What happen to -X actually being "High End Desktop" ? This is 4 cores, dual channel, restricted PCI-E lanes, nothing like the previous -X series. Only thing is it requires an expensive motherboard. WTF???
  • the nerd 389
    182243 said:
    What happen to -X actually being "High End Desktop" ? This is 4 cores, dual channel, restricted PCI-E lanes, nothing like the previous -X series. Only thing is it requires an expensive motherboard. WTF???


    You've nicely summarized the general opinion of the i7-7740x and the i5-7640x.