Intel’s direction for the high-end desktop space has taken an interesting turn. After several years of iterative updates, slowly increasing core counts and increasing IPC, we have gotten used to being at least one generation of microarchitecture behind the mainstream consumer processor families. There are many reasons for this, including enterprise requirements for long support platforms as well as enterprise update cycles. For 2017, Intel is steering the ship in a slightly different direction, and launching the latest microarchitecture on the HEDT platform. These CPUs don’t feature the high core counts of the other HEDT parts, but offer a higher point up the voltage/frequency scale to be the fastest single thread processors money can buy. They also overclock quite well.

The High-Level Product

Back at Computex, Intel announced its new high-end desktop (HEDT) platform code named Basin Falls. There are three elements to Basin Falls: the new X299 chipset which brings a number of enhancements from the more mainstream consumer line, a set of Skylake-X processors based on the Skylake-SP microarchitecture (and slightly different from the mainstream Skylake-S processors launched in 2015) from 6 cores to 18 cores, and a pair of Kaby Lake-X processors, reusing the Kaby Lake-S silicon launched earlier this year but with a bit more frequency and power consumption.

We covered all three parts in our launch pieces (linked below), but here is a quick recap.

Pushing Peak Performance

The main reasons an enthusiast invests in the HEDT platform usually revolve around multi-threaded performance, the need to support multiple graphics cards, and potentially 1.21 jiggabytes of DRAM (ed: you mean 128GB). Kaby Lake-X (KBL-X for short) doesn’t have any of these features that we normally prescribe to HEDT: it only has four cores, not ten or higher; it only supports one GPU at full PCIe speed, up to two in SLI or three in Crossfire if you are willing to have a lower link speed; and it only has dual channel memory for a maximum of 64GB. So why is Intel bringing KBL-X to HEDT? The answer lies primarily in peak performance.

Users that have been in the enthusiast space will have realized that the Holy Grail for PC performance is single threaded (ST) performance. If you master single thread throughput, then arguably the rest is easier, such as scaling out to more cores. There are usually three barriers to high ST-perf: instructions per clock (IPC), frequency and power consumption. A high IPC is fundamental to such a design, as any gains will propagate through the platform, but is becoming a tough job. Over the last few generations, Intel has increased IPC by 3-10% each generation, making a 30-45% increase since 2010 and Sandy Bridge depending on the benchmark, but we’re unlikely to see 50-100% jumps per generation any time soon. Any IPC gains are multiplied through the frequency at which the processor runs at, which can be limited by a combination of things: production process (e.g 14nm), voltage characteristics, stability, yield etc. These features tie directly into power consumption, which increases as a square of voltage and with frequency/capacitance. With some designs, +10% frequency might be possible, but at the cost of +100% power, so there also needs to be a balance to have something marketable that people will want to buy.

Kaby Lake-X is binding Intel’s latest x86 microarchitecture with the highest IPC, at the highest frequency they have ever launched a consumer CPU, for a reasonable power window. Users can overclock another 10% fairly easily, for a slight increase in power. Simply put, Kaby Lake-X is the highest single-thread performing x86 processor out-of-the-box that exists. This is a different take on HEDT compared to previous generations of HEDT CPUs.

With the extra single thread performance, it would appear to appeal to traders who need fast systems, gamers where single thread performance is limiting the frame rate (or minimum frame rates), or science/enterprise workloads where serial code is a limiting factor for simulations or professional applications.

The Core i7 and the Core i5

At the heart, the new KBL-X processors are no different to their mainstream platform KBL-S brethren. The silicon is the same, but potentially binned for a better voltage/frequency curve, and then packaged into the HEDT platform rather than the mainstream platform. Unlike the mainstream processor stack though, Intel is only launching two processors. A Core i7-7740X and a Core i5-7640X.

Intel Kaby Lake Processors
  Core i7 Core i5
Core i7-7740X Core i7-7700K Core i5-7640X Core i5-7600K
Socket LGA2066 LGA1151 LGA2066 LGA1151
Cores/Threads 4/8 4/8 4/4 4/4
Base Frequency 4.3 GHz 4.2 GHz 4.0 GHz 3.8 GHz
Turbo Frequency 4.5 GHz 4.5 GHz 4.2 GHz 4.2 GHz
TDP 112 W 91 W 112 W 91 W
L2 Cache 256 KB/core
L3 Cache 8 MB 6 MB
DRAM Channels 2
DRAM Support DDR4-2666 DDR4-2400 DDR4-2666 DDR4-2400
Graphics None HD 620 None HD 620
Price (MSRP) $350 $250
Price (7/21) $349 $309 $248 $239
Launched July 2017 Jan 2017 July 2017 Jan 2017

Both CPUs are quad core, with the Core i7 having Hyperthreading for a total of eight threads. The Core i5 does not have hyperthreading, making it the first HEDT processor in the modern Core era to do so. Both will have identical support to their KBL-S siblings, although the increased base/turbo frequencies have resulted in Intel’s TDP increasing from 95W to 112W. The TDP rating is a guide for appropriate cooling: the KBL-S processors were actually very good on their power consumption at stock frequencies, and as shown later, so are the KBL-X processors. Intel could have kept the 95W TDP rating very easily here.

So given what was said in the previous section about peak performance, the Core i7 fits the bill. It has the highest frequencies, and supports hyperthreading for increased performance. It begs the question why the Core i5 exists at all. There are a few guesses as to why:

  • For some enterprise users, hyperthreading is not needed
  • It is a cheaper entry point into the platform
  • It overclocks just as well to perform the same as the Core i7

Intel’s official line is about giving customers options. We will not be seeing a Core i3 on HEDT any time soon, though.

Kaby Lake-X does not come with any bundled cooler, but Intel is promoting its own TS13X liquid cooled loop with the processors. This CLC has been in the market for a good number of years now.

Competition and Market

Because these new KBL-X parts are updates to the KBL-S family, Intel has direct competition with itself. The Core i7-7740X is an alternative to the Core i7-7700K on the mainstream platform, being similar in frequency but giving much higher platform costs.

Comparison: Intel Core i7-7740X vs Core i7-7700K
Core i7-7740X
Features Intel
Core i7-7700K
X299 Platform Z270 etc
LGA2066 Socket LGA1151
4 / 8 Cores/Threads 4 / 8
4.3 / 4.5 GHz Base/Turbo 4.2 / 4.5 GHz
16 PCIe 3.0 Lanes 16
256 KB/core L2 Cache 256 KB/core
8 MB L3 Cache 8 MB
112W TDP 95W
$349 Retail Price (7/21) $309
MSI X299 Raider: $230
ASUS Prime X299-A: $310
GIGABYTE X299-UD4: $249
Cheap OC
GIGABYTE Z270-HD3: $114
MSI Z270 SLI PLUS: $136
ASUS TUF Z270-MK2: $120

Similar platform builds for the two put an extra $100-150 cost on the motherboard, potentially limiting the usefulness of the new KBL-X parts on paper, as that extra cost of the build as a whole might not warrant another 100 MHz on the turbo frequency. The proof is in the pudding, which is why we are doing this review. The Core i5-7640X against the Core i5-7600K is in a similar situation.

However, there is also AMD to discuss. With the launch of the Ryzen family of processors, There are now significant comparisons to be made between what Intel offers and what AMD offers. Going at a price-for-price comparison, using MSRP prices (not sale prices or distributor prices), the Core i7-7740X squares against AMD’s Ryzen 7 1700.

Comparison: Intel Core i7-7740X vs AMD Ryzen 7 1700
Core i7-7740X
Features AMD
Ryzen 7 1700
X299 Platform X370, B350, A320
LGA2066 Socket AM4
4 / 8 Cores/Threads 8 / 16
4.3 / 4.5 GHz Base/Turbo 3.0 / 3.7 GHz
16 PCIe 3.0 Lanes 16
256 KB/core L2 Cache 512 KB/core
8 MB L3 Cache 16 MB (Victim Cache)
112W TDP 65W
$349 Retail Price (7/21) $270
MSI X299 Raider: $230
ASUS Prime X299-A: $310
GIGABYTE X299-UD4: $249
Cheap OC
ASUS Prime B350-Plus: $90
MSI B350 Tomahawk: $100
ASRock AB350 Pro4: $100

At this price, both sides have their merits. Intel wins in IPC, which is about 5-15% ahead clock-for-clock, but is also at a higher frequency compounding the difference. In its own attack, AMD wins in cores and threads, offering eight cores and sixteen threads where Intel only offers four cores and eight threads. Intel wins for the IO and chipset, offering 24 PCIe 3.0 lanes for USB 3.1/SATA/Ethernet/storage, while AMD is limited on that front, having 8 PCIe 2.0 from the chipset. Depending on the workload, both sides have merits – AMD will state that it is geared towards more professional multi-threaded workloads, while Intel is geared towards serial code scenarios which still dominate certain tasks. There’s also the platform cost, where the motherboards are $150-$200 cheaper for AMD when looking at cheap overclockable systems.

For the Core i5-7640X, it sits at a similar price to AMD’s Ryzen 5 1600X.

Comparison: Intel Core i5-7640X vs AMD Ryzen 5 1600X
Core i5-7640X
Features AMD
Ryzen 5 1600X
X299 Platform X370, B350, A320
LGA2066 Socket AM4
4 / 4 Cores/Threads 6 / 12
4.2 / 4.4 GHz Base/Turbo 3.6 / 4.0 GHz
16 PCIe 3.0 Lanes 16
256 KB/core L2 Cache 512 KB/core
8 MB L3 Cache 16 MB (Victim Cache)
112W TDP 95W
$248 Retail Price (7/21) $230
MSI X299 Raider: $230
ASUS Prime X299-A: $310
GIGABYTE X299-UD4: $249
Cheap OC
ASUS Prime B350-Plus: $90
MSI B350 Tomahawk: $100
ASRock AB350 Pro4: $100

For this review, we have also included numbers for other processors. These include AMD’s Ryzen 7 1800X, which at $499 is an alternative due to the money saved by investing on the AM4 platform; we also have the Skylake-X based Core i7-7800X, which has an MSRP not so far away from the i7-7740X, and opens up the platform with more PCIe lanes, two more cores, but at the expense of single thread performance; and finally the perennial Core i7-2600K from the Sandy Bridge era, for the benchmarks which we have data.

Given everything said above, it would appear Intel has an uphill struggle to convince users that Kaby Lake-X is worth the investment. In this review we will test and see what the performance story is.

Please note that our AMD data is before AGESA We are planning an article with an update of the latest AGESA soon.

Pages In This Review

Navigating the X299 Minefield: Kaby Lake-X Support


View All Comments

  • mapesdhs - Monday, July 24, 2017 - link

    Ok, you get a billion points for knowing Commodore BASIC. 8) Reply
  • IanHagen - Monday, July 24, 2017 - link

    Dr. Ian, I would like to apologize for my poor choice of words. Reading it again, it sounds like I accused you of something which is not the case.

    I'm merely puzzled by how Ryzen performs poorly using msvc compared to other compilers. To be honest, your finds are very relevant to anyone using Visual Studio. But again, I find Microsoft's VS compilar to be a bit of an oddball.

    A few weeks ago I was running my own tests to determine wether my Core i5 4690K was up to my compiling tasks. Since most of my professional job sits on top of programming languages with either short compile times or no compilation needed at all, I never bothered much about it. But recently I've been using C++ more and more during my game development hobby and compile times started to bother me. What I found puzzling is that after running a few test I couldn't manage to get any gains through parallelism, even after verifying that msvc was indeed spanning all 4 threads to compile files. Than I tried disabling two cores and clocking the thing higher and... it was faster! Not by a lot, but faster still. How could it be faster with a 50% decrease in the number of active cores and consequently threads doing compile jobs? I'm fully aware that linking is single threaded, but at least a few seconds should be gained with two extra cores, at least in theory. Today I had the chance to compile the same project on a Core i7 7700HQ and it was substantially slower than my Core i5 4690K even with clocks capped to 3.2 GHz. In fact, it was 33% slower than my Core i5 at stock speeds.

    Anyhow… Dr. Ian’s findings are a very good to point out to those compiling C++ using msvc that Skylake-X is probably worth it over Ryzen. For my particular case, it would appear that Kaby Lake-X with the Core i7 7740X could even be the best choice, since my project somehow only scales nicely with clocks.

    I just would like to see the wording pointing out that Skylake-X isn’t a better compiling core. It’s a better compiling core using msvc at this particular workload. On the GCC side of things, Ryzen is very competitive to it and a much better value in my humble opinion.

    As for the suggestion, I’d say that since Windows is a requirement trying to script something to benchmark compile times using GCC would be daunting and unrealistic. Not a lot of people are using GCC to work on the Windows side of things. If Linux could be thrown into the equation, I’d suggest a project based on CMake. That would make it somewhat easy to write a simple script to setup, create a makefile and compile the project. Unfortunately, I can not readily think of any big name projects such as Chromium that fulfill that requirement without having to meddle with eventual dependency problems as the time goes by.
  • Kevin G - Monday, July 24, 2017 - link

    These chips edge out their LGA 1151 counter parts at stock with overclocking also carrying a slight razor edge over LGA 1151 overclocks. There are gains but ultimately these really don't seem worth it, especially in light of the fragmentation that this causes the X299 platform. Hard to place real figures on this but I'd wager that the platform confusion is going to cost Intel more than what they will gain with these chips. Intel should have kept these in the lab until they could offer something a bit more substantial. Reply
  • mapesdhs - Monday, July 24, 2017 - link

    I wonder if it would have been at least a tad better received if they hadn't cripplied the on-die gfx, etc. Reply
  • DanNeely - Tuesday, July 25, 2017 - link

    LGA2066 doesn't have video out pins because it was originally designed only for the bigger dies that don't include them; and even if Intel had some 'spare' pins it could use adding video out would only make already expensive mobos with a wide set of features that vary based on the CPU model even more expensive and more confusing. Unless they add a GPU to either future CPUs in the family (or IMO a bit more likely) a very basic one to a chipset variant (to remove the crappy one some server boards add for KVM support) keeping the IGP fully off in mainstream dies on the platform is the right call IMO. Reply
  • DrKlahn - Monday, July 24, 2017 - link

    Great article, but the conclusion feels off:

    "The benefits in the benchmarks are clear against the nearest competition: these are the fastest CPUs to open a complex PDF, at the top for office work, and at the top for most web interactions by a noticeable amount."

    In most cases you're talking about a second or less between the Intel and AMD systems. That will not be noticeable to the average office worker. You're much more likely to run into scenarios where the extra cores or threads will make an impact. I know in my own user base shaving a couple of seconds off opening a large PDF will pale in comparison to running complex reports with 2 (4 threads) extra cores for less money. I have nothing against Intel, but I struggle to see anything in here that makes their product worth the premium for an Office environment. The conclusion seems a stretch to me.
  • mapesdhs - Monday, July 24, 2017 - link

    Indeed, and for those dealing with office work it makes more sense to emphasise investment where it makes the biggest difference to productivity, which for PCs is having an SSD (ie. don't buy a cheap grunge box for office work), but more generally dear god just make sure employees have a damn good chair to sit on and a decent IPS display that'll be kind to their eyes. Plus/minus 1s opening a PDF is a nothingburger compared to good ergonomics for office productivity. Reply
  • DrKlahn - Tuesday, July 25, 2017 - link

    Yeah an SSD is by far the best bang for the buck. From a CPU standpoint there are more use cases for Ryzen 1600 than there is the i5/i7 options we have from HP/Dell. Even the Ryzen 1500 series would probably be sufficient and allow even more per unit savings to put into other areas that would benefit folks more. Reply
  • JimmiG - Monday, July 24, 2017 - link

    The 7740X runs at a just over 2% higher clock speed than the 7700X. It can overclock maybe 4% higher than the 7700X. You'd really have to be a special kind of stupid to pay hundreds more for an X299 mobo just for those gains that are nearly within the margin of error.

    It doesn't make sense as a "stepping stone" onto HEDT either, because you're much better off simply buying a real HEDT right away. You'll pay a lot more in total if you first get the 7740X and then the 7820X for example.
  • mapesdhs - Monday, July 24, 2017 - link

    Intel seems to think there's a market for people who buy a HEDT platform but can't afford a relevant CPU, but would upgrade later. Highly unlikely such a market exists. By the time such a theoretical user would be in a position to upgrade, more than likely they'd want a better platform anyway, given how fast the tech is changing. Reply

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