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8th Generation Intel Core i7-8700K Desktop Processor

  • Wednesday, December 20, 2017, 2:32 pm
  • ACROFAN=Yong-Man Kwon
Since the introduction of the first-gen core processor, despite significant performance enhancements over the past seven generations, the technological composition of the core processor in the mainstream class platform has been maintained steadily, including the number of cores in each product group. Although the 7th generation core processor has begun to show signs of change, Intel has combined two cores with four threads on core i3, four cores with four threads and turbo boost on Core i5, and four cores with eight threads on Core i7, which have been successful combinations in many ways.

However, the 8th generation core processor, which seems to be appeared a bit hasty than usual, is more prominent changes at the outside of the processor than inside the processor. Unlike before, which used the same architecture across the entire product family, the three architectures coexist in this generation. In addition, providing a significant improvement in performance compared to the previous generation could be a great feature, by increasing the number of cores provided for each product group by two in 8 generations after the first core processor.

The 8th generation Intel Core processor for the desktop has been known by the code name "Coffee Lake" and features two more cores than the previous generation. Core i7-8700K processor, which is presented as the flagship of its kind, has the first 6-core 12-thread configuration on Intel's mainstream processors, while maintaining high operating speeds and TDP as the previous generation of quad core. It can be used with 300 series chipset based mainboards, and the new mainboard offers some new features in overclocking.

▲ The 8th generation core processor family has appeared with a different look than before.

Over the past few generations, the core processor family has largely been based on the same architecture in same generation, and the code name of the architecture could be used as a generic code name of the generation. Moreover, within a few years since the first gen core processor, the 8th generation core processor family has become a product family that encompasses multiple architectures and codenames into one even in PC processors. Among the four product families, it is known that refresh of 'Kaby Lake' will be put into U-series such as notebooks, 'Coffee Lake' into H-series such as high-performance notebooks, all-in-one and S-series such as desktop, and 'Cannon Lake' into Y-series for ultra low power notebooks.

These three architectures are put together, but they should offer a standard performance of consistent core in the same generation. Hereupon, the difference between the three microarchitectures seems to be come from product enhancements such as packaging changes rather than the architecture itself. Intel presented refresh of the existing ‘Kaby Lake’ as a 4-core 8-thread with 15W TDP in the U-series on 8th generation core processors, while presenting ‘Coffee Lake’ with 6-core 12-tread by reorganizing the existing architecture in the S-series for desktops. These are all ‘8th core processors’.

Except for changes in the number of cores and threads, it is not easy to find a noticeable difference in function or performance between the 7th gen and the 8th generation core processor. The built-in GPU, which is based on the existing 9th generation, is known to have a change of supporting HDCP 2.2 for UHD environment at GPU itself, with a slight increase in the operation speed. Also, the model name was changed to UHD graphics 630 from HD graphics 630. In addition to this, a platform change might be DDR4-2666 support and official removal of DDR3L support.

▲ The 8th generation core processor family for desktops is also the first 6-core processor in the mainstream. (Source: Intel)

While the Core i7-8700K, which is the top-of-the-line model of the 8th generation core processor for desktops, has the first 6-core 12-thread configuration in Intel's mainstream platform-based 'core' branded processors, with a default operating speed of 3.7GHz and up to 4.7GHz by turbo boost 2.0, and TDP is defined as 95W as to the K-series processors of the previous generation. Even though the number of cores has increased, the operating speed at similar conditions is slightly higher than the previous generation, which guarantees higher performance than the previous generation under any circumstances.

So far, configurations of six or more cores have been mentioned as reasons for using the HEDT platform, and there are a few real reasons for this. The main reason is that as the number of cores increases, the operating speed decreases under the condition of limited power and heat. This is because it is directly related to the performance problem in a PC environment that does not utilize the multi-thread structure properly. Finally, for a variety of reasons, the time for multi-core environments with more than four cores to have enough competitiveness. The current 6-core 12-thread processor with high operating speed expects a more than 40% increase in performance compared to the previous generation in multithreaded applications, and competitiveness to compete with the current 8-core HEDTs.

By remaining the same configuration of LLC per processor core as in the previous generation, the Core i7-8700K has a total of 12MB configuration with 2MB per core. The processor's built-in dual-channel memory controller has been changed to up to DDR4-2666 specification supports, and the DDR3L memory support option offered on previous generation platforms has been removed from this generation. Sockets use the same number of pins as previous generations, but inter-socket compatibility is not possible internally due to pin array changes, such as power supply reinforcement to accommodate two more cores. It can also be used with mainboards based on the new 300 series chipset.

As the architecture of the core itself has not changed significantly, the instruction set that the processor supports is maintained at the previous generation level. While the HEDT platform's ‘core X-series’ processors except 4-core models support the AVX-512, the 8th-generation core processor still uses the 256-bit wide AVX2. Of course, encouraging more active use of the current AVX2 is also one of Intel's oldest homework assignments. In addition, the various instruction sets introduced in previous generations such as VTs, AES-NI, and TSX are all included.

▲ The existing Gen9 LP GT2 core is used, but new HDCP 2.2 support has been added. (Source: Intel)

The processor built-in graphics core, like the existing 6th and 7th generation core processors, uses a GT2 core with 24 EUs based on the ninth-generation architecture. Interestingly, the product name of the graphics core of this generation is 'UHD Graphics 630'. The number is still the same in the model name, but only the text has changed from HD to UHD. And the reason for this small change is that there was an update to support HDCP 2.2 without DP (DisplayPort) or a separate external chip combination in HDMI 1.4.

As with previous generations, the 8th generation core processor supports up to three 4K outputs, of which specification of HDMI output is HDMI 1.4 and only supports 30Hz at output of 4K. The 4K 60Hz and HDR outputs are supported on the output of the DP standard, and the current HDMI 2.0 is configured in form of using the HDMI 2.0a converter on the DP output, and the HDCP 2.2 also uses the external chipset. However, as HDCP 2.2 is supported at the processor level, it will be available immediately at no additional cost from HDMI 1.4 or DP outputs.

Meanwhile, the upcoming ‘Cannon Lake’ based Y and U-series 8th generation core processors are expected to include a new generation of GPUs with improved functionality and performance. Intel's GPU-related strategies have also changed slightly. Starting from the introduction of the 8th Gen core processor, it had been introduced that performance enhancements of built-in graphics cores mainly in Y and U-series, which are low power and mobile platforms. Its realistic reason is that it is common to have high-performance external graphics cards such as high-performance gaming desktop market, where the H and S-series are mainly used.

▲ 8th generation core processors can be used with new 300 series chipset-based mainboards.

The 8th generation core processor can be used with mainboards based on the 300 series chipsets, while the socket maintains the existing LGA 1151 specification, resulting in cost savings in terms of manufacturing and design. Of course, the same physical standards do not provide compatibility with previous generations, since pin arrangements have changed quite a bit depending on the number of cores added. In fact, this were some cases in the history. Among them, a recent case is that the previous mainboard could not be used at all due to chipset compatibility and VRM specification changes when switching from Intel's Pentium 4 LGA 775 socket and 915 chipset based to Pentium D.

The 300 series chipset, which emerged with the announcement of the eighth-generation core processor, is now one, which is Z370, and is expected to feature new chipsets from H310 to Z390 in the future. Z370 is a refresh model of the chipset used internally in the existing 200 series, and it does not show much difference in function and performance from the existing Z270. However, with the official support of the 8th generation core processor, there are changes such as new overclocking related functions, next generation Optane memory, and support for new software based functions in RST.

The features of New overclocking, which is provided from 300 series chipset based mainboards, are securement of more headrooms for overclocking through increased package power delivery, extension of maximum memory operation speed definition up to 8,400MT/s, and availability of memory latency control in real time on the operating system. In addition, PLL trim control has been extended with core control to ring, memory controller, system agent and GT PLL, and it is also possible to specify the overclocking limit per core. Meanwhile, a reporting function on the initial turbo boost limit has been added to allow more sophisticated progression.

▲ Test System Specification

The biggest feature of the 8th generation Intel Core i7-8700K processor is that it provides the highest performance in both single-thread and multi-thread environments by offering 6-core 12-thread configuration on the mainstream PC platform for the first time and high operating speed. Especially, that 8th generation core processor maintains the high operating speed with the extension to 6-core rather than 8-core could be seen as a realistic choice for maximizing the performance in the latest gaming environment.

The test identified aspects of advantages as two cores are increased, by comparing with 'Kaby Lake' based 4-core processor in terms of the basic processor operation performance or the overall system configuration. The Core i7-8700K processor, which has 6-core 12-threads and up to 4.7GHz operating speed, is a threat to 6-8 core processors of the HEDT platform, which performs relatively low operating speed, as well as the previous generation products.

The test system uses Intel Core i7-8700K processor and ASUS TUF Z370 PLUS GAMING mainboard based on the Z370 chipset. The memory uses four 8GB modules with operating speed of DDR4-2666 and configures 32GB as a dual channel. The operation speed of the processor uses the automatic setting value of the mainboard and its graphic uses the same one as processor built-in graphic. The storage uses Intel's 525 series 120GB model, and the operating system utilizes the latest version of Windows 10 RS2 version and drivers provided on the mainboard.

▲ SiSoft Sandra 2017 SP1 (Processor Arithmetic) test result, the higher the better

▲ SiSoft Sandra 2017 SP1 (Processor Multimedia) test result, unit Mpix/s, the higher the better

▲ SiSoft Sandra 2017 SP1 (Memory Bandwidth) test result, unit GB/s, the higher the better

The result of SiSoft Sandra 2017 SP1, which shows the basic performance of the processor, shows a significant improvement in performance compared to Core i7-7740X, which has a similar operating speed. In general operating performance, Core i7-8700K with 6-core 12-thread shows 44% higher performance than i7-7740X with 4-core 8-thread, and the performance difference of about 6% compared to 50% higher number of cores is due to differences in operating speed when full loaded. Moreover, it also shows that i7-8700K maintains a high operating speed of 4GHz or faster, even under full load of a 6-core 12-thread.

Even in multimedia performance tests using AVX, Core i7-8700K is up to 47% better than the i7-7740X, which almost reflects only the differences in the number of core and thread, and in operating speed. Accordingly, although the operation efficiency of 'Coffee Lake'-based 8th generation core processor is not much different from 'Kaby Lake'-based 7th generation core processor, the performance difference at practical product level shows fairly clear difference with increased cores and threads, and increased memory performance. What made this possible is thanks to the more refined process technology.

The dual-channel DDR4-2666 memory controller of Core i7-8700K now records transfer rates of over 30GB/s on dual channels, and the HEDT platform shows a difference within degrees of an error range from Core i7-7740X's DDR4-2666 memory controller. This improved memory performance not only affects the performance of the processor and platform, but also the performance of the built-in graphics cores. In particular, when a number of high resolution displays are connected, the memory performance determined its availability as well as its performance.

▲ 3DMark (Firestrike) test result, the higher the better

▲ 3DMark (Time Spy) test result, the higher the better

▲ PCMark 10 (Extended Test) test result, the higher the better

In 3DMark's Firestrike test, which can figure out system gaming performance, Core i7-8700K's built-in graphics core scored a total of 1374 points, slightly higher than the score of the 7th generation core processor's built-in graphics cores. Even though there has been little or no change that might affect the performance at the graphics core level, the performance improvements are due to slightly higher operating speeds, a faster memory controller, a larger total number of LLCs, and continuously improved drivers.

Meanwhile, in Firestrike's processor physics score, Core i7-8700K recorded 33% better performance than Core i7-7700K, and the score itself was close to catching up with the previous generation's 8-core HEDT processors, and when compared with Core i5-7600K, the performance was more than double. However, CPU score of Time Spy shows 20% higher performance so that the width of the performance improvement seems to decrease, and the gap with the HEDT class processors also naturally increases. Of course, given the fact that the i9-7900X of the current HEDT platform is slightly above 10,000 points, it can be seen as a reasonable result considering the number of cores.

Extended testing of PCMark 10 measures overall system performance through various scenarios that reflect relatively recent environments. In this test, Core i7-8700K shows evenly high performance over the entire range. In case of using a separate graphics card, the significantly improved results could be gained in digital content production and gaming. Compared to the mainstream quad-core processors, Core i7-8700K showed significant performance differences in areas where multicore benefits are evident, such as video editing.

▲ SYSMark 2014 SE test result, the higher the better

▲ Cinebench R15 test result, the higher the better

▲ Intel Linpack (2017.3.020) test result, the higher the better

In BAPCo's SYSmark 2014 SE test results, which measure performance based on programs that are actually used, Core i7-8700K based system showed a clear performance difference compared to the i7-7700K based system. Performance differences in the basic office environment were not great, but in the areas of media creations and data analysis, more cores and threads showed a clear performance improvement, and the overall results showed a considerable increase by reflecting it. Moreover, even when considering the reactivity side, the high-speed 6-core configuration is an option that can be quite balanced in the current PC environment.

Meanwhile, in the test results of Cinebench R15, which confirms the performance of the processor, Core i7-8700K has achieved 45% higher performance than Core i7-7700K. In particular, the 6-core 12-thread configuration also showed 80% performance of Core i7-6950X, which is the previous-generation HEDT 10-core 20-thread configuration. This shows that it is similar to the performance of both present and previous 6- to 8-core HEDT processors. Moreover, as the performance is made with less cores and simple structure, the sensory performance in the actual use environment seems to be higher than this.

In addition, in tests of 2017.3.020 version of Intel Linpack that confirms processor's AVX2 operation performance, Core i7-8700K is 46% higher than Core i7-7740X, and when compared to i7-6950X, its performance was close to 80% of the performance. On the other hand, there is no difference in performance between the latest library and the 2017 version on AVX2-based processor, but the AVX2 performance difference in the latest processors between the library several years ago and the latest library is quite large.

▲ Specification of Intel Core i7-8700K

When thinking of the history of core processors, there may be some controversy as to whether this 8th generation core processor can be called the "eighth generation." 'Coffee Lake' for desktop PCs is almost the same to the previous generation 'Kaby Lake' technically both core and iGPU. However, from the viewpoint of "product", it is clear that the 8th generation core processor has achieved the greatest performance improvement among generations of recent years with two more cores than the previous generation.

The 8th generation core processor might be, in some ways, the result of responding to the changes of the times in the simplest way. As the importance of multithread performance has increased significantly, adding two more cores to the major product line might have been judged that the environment has changed that more cores can deliver enough value. Along with this trend, the appropriate use of an 'accelerator' is expected to create an environment that can steadily lead Moore's Law, which once had a crisis theory, in a broad sense. Of course, it was able to catch this opportunity because there was progress in the process and low power related performance.

Meanwhile, at the time of the announcement of the 8th generation core processor and the platform, one thing to be desired is a 'mainboard'. While the processors are all presented from Core i3 to i7, the fact that Z370s, which is relatively expensive, is the only mainboard chipset presented is a part that makes us hesitate to purchase in terms of cost. For this reason, demand for 8th generation core processors in the second half of this year will be centered on 'K series' high-end models, and if chipsets for mid-priced mainboards are introduced in the future, it is expected that they will replace 7th generation core processors and the previous PCs faster than ever.