Intel 7th Generation Core Processor: Kaby Lake Revealed
What's new and what's not
While spending time learning about upcoming products and technologies at the Intel Developer Forum earlier this month, I sat down with the company to learn about the release of Kaby Lake, now known as the 7th Generation Core processor family. We have been seeing and reporting on the details of Kaby Lake for quite some time here on PC Perspective – it became a more important topic when we realized that this would be the product that officially killed off the ‘tick-tock’ design philosophy that Intel had implemented years ago and that was responsible for much of the innovation in the CPU space over the last decade.
Today Intel released new information about the 7th Gen CPU family and Kaby Lake. Let’s dive into this topic with a simple and straight forward mindset in how it compares to Skylake.
What is the same
Actually, quite a lot. At its core, the microarchitecture of Kaby Lake is identical to that of Skylake. Instructions per clock (IPC) remain the same with the exception of dedicated hardware changes in the media engine, so you should not expect any performance differences with Kaby Lake except with improved clock speeds we’ll discuss in a bit.
Because of this lack of change many people will look down on the Kaby Lake release as Intel’s attempt to repackage an existing product to make sure it meets a financial market required annual product cadence. It is a valid but arguable criticism, but Intel is making changes in other areas that should make KBL an improvement in the thin and light ecosystem.
Also worth noting is that Intel is still building Kaby Lake on 14nm process technology, the same used on Skylake. The term “same” will be debated as well as Intel claims that improvements made in the process technology over the last 24 months have allowed them to expand clock speeds and improve on efficiency
What is changed
Dubbing this new revision of the process as “14nm+”, Intel tells me that they have improved the fin profile for the 3D transistors as well as channel strain while more tightly integrating the design process with manufacturing. The result is a 12% increase in process performance; that is a sizeable gain in a fairly tight time frame even for Intel.
That process improvement directly results in higher clock speeds for Kaby Lake when compared to Skylake when running at the same target TDPs. In general, we are looking at 300-400 MHz higher peak clock speeds in Turbo Boost situations when compared to similar TDP products in the 6th generation. Sustained clocks will very likely remain voltage / thermally limited but the ability spike up to higher clocks for even short bursts can improve performance and responsiveness of Kaby Lake when compared to Skylake.
In these two examples, Intel compares the 15 watt Core i7-6500U (a common part in currently shipping notebooks) and the upcoming 15 watt Core i7-7500U, both with dual-core HyperThreaded configurations. In SYSmark 2014 a 12% score improvement is measured while WebXPRT shows a 19% advantage. Double digit performance increases are pretty astounding for a new generational jump that does not include a new microarchitecture or a new process technology (more or less) though we should temper expectations for other applications and workload profiles like content creation.
Along with higher fixed clock speeds for Kaby Lake processors, tweaks to Speed Shift will allow these processors to get to peak clock speeds more quickly than previous designs. I extensively tested Speed Shift when the feature was first enabled in Windows 10 and found that the improvement in user experience was striking. Though the move from Skylake to Kaby Lake won’t be as big of a change, Intel was able to improve the behavior.
This sample data shows the Kaby Lake Core i7-7500U hitting its peak clock rate of 3.5 GHz in just 15ms, while the Skylake Core i7-6500U takes about 30ms to hit its peak of 3.1 GHz. Meanwhile, the same 6500U with Speed Shift disabled takes over 90ms to reach its highest clock, reducing responsiveness for systems, especially those that depend on tough interaction.
The primary change to KBL comes in the media engine where native 4K has been fully integrated.
The graphics architecture and EU (execution unit) layout remains the same from Skylake, but Intel was able to integrate a new video decode unit to improve power efficiency. That new engine can work in parallel with the EUs to improve performance throughput as well, but obviously at the expensive of some power efficiency.
Specific additions to the codec lineup include decode support for 10-bit HEVC and 8/10-bit VP9 as well as encode support for 10-bit HEVC and 9-bit VP9. The video engine adds HDR support with tone mapping though it does require EU utilization. Wide Color Gamut (Rec. 2020) is prepped and ready to go according to Intel for when that standard starts rolling out to displays.
Performance levels for these new HEVC encode/decode blocks is set to allow for 4K 120mbps real-time on both the Y-series (4.5 watt) and U-series (15 watt) processors.
The resulting changes when comparing Kaby Lake and Skylake are going to be impressive for anyone looking to playback local or streaming 4K content. This graphic compares the SoC power draw of a local playback 4K 10-bit video file: the 6th Generation processor uses over 10 watts on average to playback the video with ~50% CPU utilization. The dedicated hardware block in the 7th Generation processor lowers that to 0.5 watts and ~4% CPU utilization, offering up 2.6x the battery life for consumers.
A similar improvement is seen when playing back VP9 4K video from YouTube. Power draw drops from 5.8 watts to 0.8 watts while CPU utilization goes from 80% to ~15% as you move from the 6500U (Sky Lake) to the 7500U (Kaby Lake).
What is available now
Starting next month, systems based on Kaby Lake will be shipping from OEMs like Lenovo, Acer, ASUS and others and Intel expects there to be more than 100 designs on the market in Q4 of this year. A total of six processors are shipping now, three each of the U-series and Y-series.
The 15-watt U-series of processors will be found in the vast majority of the next generation of thin and light notebooks and convertibles including some of our favorites like the Dell XPS 13 and Lenovo Yoga ThinkPad. All three are 2-core/4-thread designs though clock speeds vary. The Core i3-7100U does NOT include support Turbo Boost and instead will run at a fixed 2.4 GHz under load, the Core i5-7200U will clock from 2.5 GHz to 3.1 GHz and the Core i7-7500U will run at 2.7 GHz up to 3.5 GHz. All three platforms utilize DDR3L or LPDDR3 memory at 1600-1866 MHz or they can integrate DDR4 memory at up to 2133 MHz.
The lower power, 4.5 watt processors are also 2-core/4-thread designs but have much wider ranges of clock speeds in order to fit into that adjusted and configurable thermal envelope. The Core m3-7Y30 has a base clock of just 1.0 GHz but can boost as high as 2.6 GHz! Interestingly, Intel has gone away with the m5/m7 designation (and least for this release) and the next two higher models of Y-series parts are Core i5/i7 branded instead. The Core i5-7Y54 clocks from 1.2 GHz up to 3.2 GHz while the Core i7-7Y75 range goes from 1.3 GHz to 3.6 GHz, making it (technically) the highest clock speed part announced today. Of course, it won’t maintain that high of a clock rate for very long in the types of chassis built around 4.5 watt processors.
I expect to start seeing 7Th Generation notebooks and 2-in-1s in our offices very soon for testing, where we will be able to do some hands on testing with the new 4K video capabilities and to measure the expected performance improvements that Kaby Lake will offer.
What is coming next year
In January 2017, likely at CES, we will start to see the release of other products based on the Kaby Lake design, including consumer, enterprise, workstation and processors that integrate Iris-style graphics systems. We really don’t have any more data than that to share but you will definitely see Kaby Lake K-series processors to overtake the Skylake K-series parts currently on the market. How high they will clock and how much they will improve on currently shipping products will be interesting to see. Could we actually see the same 300-400 MHz clock speed improvements on the desktop?
Y-series Kaby Lake
Despite getting the incremented brand of being the 7th Generation Core processor design, Kaby Lake sees a less impressive technological shift than we have come to expect. The move away from the ‘tick-tock’ model into the ‘tick-tock-optimize’ scheme is a result of combined technology and business directions, but the added performance available courtesy of clock speed increases and 4K media improvements will at least offer some differentiation between previous and upcoming systems. It will vary between different user workloads, but peak clock speed increases of >12% are going to improve the computing experience for the vast majority of consumers.