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Skylake (microarchitecture)

Skylake is the codename used by Intel for the 6th[6] generation Core processor microarchitecture which was launched in August 2015[7] as the successor to the Broadwell microarchitecture.[8] Skylake is a microarchitecture redesign using an already existing process technology, serving as a "tock" in the Intel's "tick-tock" manufacturing and design model. According to Intel, the redesign brings greater CPU and GPU performance and reduced power consumption. Skylake uses the same 14 nm manufacturing process[9] as Broadwell.

An initial batch of Skylake CPUs (6600K and 6700K) was announced for immediate availability during theGamescom on August 5, 2015,[1] unusually soon after Broadwell. While the industry observers initially believed that the issues[10] impacting Broadwell would also affect Skylake, newer information suggests that Intel will be seeking to recover by maintaining the traditional "tick-tock" cadence for Skylake and shortening Broadwell's release cycle instead. Other CPUs based on this architecture will be released later in 2015.[11]

Intel states that Skylake is its "most significant processor" for a decade, due to the enhanced power efficiency and wire-free capabilities.[12][13]

 

 

Development history[edit]

Skylake's development was primarily undertaken by Intel Israel,[14] centered at its engineering research center in Haifa, Israel, as with processors such as Banias, Dothan, Conroe, Sandy Bridge and Ivy Bridge. The Israeli team is the same Haifa task force that designed the Sandy Bridge and Ivy Bridge microarchitecture. The team has been working on the project for four years, and faced many challenges: "But by re-writing the micro-architecture and developing new concepts such as the Speed Shift Technology, we created a processor for 4.5 W...45 W mobile devices, and up to 91 W for desktop devices."[15] The Skylake processors will be used to power a wide range of devices, from smart phones, tablets, all the way to desktops.[16] "Because of Skylake's features, companies will be able to release laptop PCs that are half as thick and half as heavy as those from five years ago, according to Intel."[17]

Features[edit]

Like its predecessor, Broadwell, Skylake is available in four variants, identified by the suffixes "S" (SKL-S), "H" (SKL-H), "U" (SKL-U), and "Y" (SKL-Y). SKL-S contains an overclockable "K" variant with unlocked multipliers.[18] The H, U and Y variants will be manufactured in ball grid array (BGA) packaging, while the S variant will be manufactured in land grid array (LGA) packaging using a new socket, LGA 1151.[19] Skylake is used in conjunction with Intel 100 Series chipsets, also known as Sunrise Point.[20]

The major changes between the Haswell and Skylake architectures include the removal of the fully integrated voltage regulator (FIVR) introduced with Haswell,[21] and the integration of the Platform Controller Hub (PCH) onto the die for Skylake's H, U and Y variants, effectively following a system-on-chip (SoC) design layout. The S variant remains a two-chip design. On the variants that will use a discrete PCH, Direct Media Interface (DMI) 2.0 is replaced by DMI 3.0, which allows speeds of up to 8 GT/s.

Skylake's U and Y variants support one DIMM slot per channel, while H and S variants support two DIMM slots per channel.[19] Skylake's launch and sales lifespan occur at the same time as the ongoing SDRAM market transition, with DDR3 SDRAM memory gradually being replaced by DDR4memory. Rather than working exclusively with DDR4, the Skylake microarchitecture remains backward compatible by interoperating with both types of memory. Accompanying the microarchitecture's support for both memory standards, a new SO-DIMM type capable of carrying either DDR3 or DDR4 memory chips, called UniDIMM, was also announced.[22]

Other enhancements include Thunderbolt 3.0, SATA Express, Iris Pro graphics with Direct3D feature level 12_1 with up to 128 MB of L4 eDRAMcache on certain SKUs.[23] The Skylake line of processors retires VGA support,[24] while supporting up to five monitors connected via HDMI 1.4, DisplayPort 1.2 or Embedded DisplayPort (eDP) interfaces.[25] HDMI 2.0 (4K@60 Hz) is only supported on motherboards equipped with Intel’s Alpine Ridge Thunderbolt controller.[26]

The Skylake instruction set changes include Intel MPX (Memory Protection Extensions) and Intel ADX (Multi-Precision Add-Carry Instruction Extensions). The Xeon variant also has Advanced Vector Extensions 3.2 ("AVX-512F").[2][3]

Skylake-based laptops may use wireless technology called Rezence for charging, and other wireless technologies for communication with peripherals. All major PC vendors have agreed to use this technology in Skylake-based laptops, which should be released by the end of 2015.[27]

Integrated GPU of the Skylake's S variant support DirectX 12 Feature Level 12_1, OpenGL 4.4 and OpenCL 2.0 standards, as well as some modern hardware video encoding/decoding formats such as VP9 (GPU accelerated decode only), VP8 and HEVC (hardware accelerated 8-bit encode/decode and GPU accelerated 10-bit decode).[28][29][30]

Intel released unlocked (capable of overclocking) mobile Skylake CPUs for the first time ever.[31]

Architecture[edit]

  • 14 nm manufacturing process[6]
  • LGA 1151 socket
  • 100 Series chipset (Sunrise Point)[32]
  • Thermal design power (TDP) up to 95 W (LGA 1151)[33]
  • Support for both DDR3L SDRAM and DDR4 SDRAM in mainstream variants, using custom UniDIMM SO-DIMM form factor[34][35][36] with up to 64 GB of RAM on LGA 1151 variants. Usual DDR3 memory is also supported by certain motherboard vendors even though Intel doesn't officially support it.[37][38]
  • Support for 16 PCI Express 3.0 lanes from CPU, 20 PCI Express 3.0 lanes from PCH (LGA 1151)
  • Support for Thunderbolt 3.0 (Alpine Ridge)[39]
  • 64 to 128 MB L4 eDRAM cache on certain SKUs
  • Up to four cores as the default mainstream configuration[34]
  • AVX-512 F, CDI, VL, BW, and DQ for the Xeon variants[2]
  • Intel MPX (Memory Protection Extensions)
  • Skylake's integrated Gen9 GPU supports Direct3D 12 at the feature level 12_1[40][41]
  • Full fixed function HEVC Main/8bit encoding/decoding acceleration. Hybrid/Partial HEVC Main10/10bit decoding acceleration. JPEG encoding acceleration for resolutions up to 16,000x16,000 pixels. Partial VP9 encoding/decoding acceleration.[42]

Configurations[edit]

Skylake processors will be produced in four main families: Y, U, H and S. Multiple configurations will be available within each family:[19]

  • Integrated L4 cache will be available with various Skylake-U, H and S configurations.
  • The S variant is intended to be the main socketable desktop Skylake, and will have configurable thermal design power (cTDP); this allows certain Skylake chips to switch their operation between 35 W and 95 W modes.
  • A high-performance 95 W TDP Skylake-S chip will be available, but only without the L4 cache.
  • Y, U and H chips are intended for mobile or embedded systems that require lower power consumption.
  • Y and U variants will support only low-power DDR3 SDRAM, while DDR4 SDRAM will also be supported by H and S variants.

As of May 2015, more Skylake processors have appeared in available Intel roadmaps.[43][44][45][46][47][48][49]

Announcement[edit]

In September 2014, Intel announced Skylake microarchitecture at the Intel Developer Forum in San Francisco. Intel announced that volume shipments of Skylake CPUs are scheduled for the second half of 2015. Also, Skylake development platform is announced to be available in H1 2015. During the announcement, Intel also demonstrated two computers with desktop and mobile Skylake prototypes; the first one was a testbed system, running the latest version of 3DMark, while the second computer was a laptop, playing 4K video.[50]

Release timing[edit]

An unusual feature of Skylake's release timing is that it follows very closely on the release of its predecessor, Broadwell, which had suffered from launch delays.[51] Intel acknowledged in 2014 that moving from 22 nm (Haswell) to 14 nm (Broadwell) had been its most difficult process to develop yet, causing Broadwell's planned launch to slip by several months;[52] yet, the 14 nm production was back on track and in full production as of Q3 2014.[53] Industry observers had initially believed that the issues impacting Broadwell would also cause Skylake to slip to 2016, but Intel was able to bring forward Skylake's release and shorten Broadwell's release cycle instead.[10][54] Accordingly, it is believed that Broadwell will have an unusually short run.[10]

List of Skylake processors[edit]

Desktop processors[edit]

Two desktop processors were released by Intel at Gamescom on August 5, 2015.[55]

The remaining desktop processors will be released toward the end of the month at the Intel Developer Forum, with laptop and tablet CPUs coming in Q3 2015.[56]

List of announced desktop processors (see talk section):

Target
segment		 Cores
(Threads)		 Processor
Branding & Model		 CPUClock Rate CPU Turbo Clock Rate GPU Model Graphics Clock Rate L3
Cache		 Max # of PCIe Lanes TDP Release
Date		 Release
Price
(USD)		 Motherboard
Single Core Dual Core Quad Core Normal Turbo Socket Interface Memory (non-ECC)
Performance 4 (8) Core i7 6700K 4.0 GHz 4.2 GHz 4.0 GHz 4.0 GHz HD 530 350 MHz 1150 MHz[57] 8 MB 16 91 W August 5, 2015 $339 LGA
1151		 DMI 3.0
PCIe 3.0		 Dual channel
DDR3L-1600 or
DDR4-2133
6700 3.4 GHz 4.0 GHz 3.9 GHz 3.7 GHz 65 W September 1, 2015 $303
Mainstream 4 (4) Core i5 6600K 3.5 GHz 3.9 GHz 3.8 GHz 3.6 GHz 6 MB 91 W August 5, 2015 $242
6600 3.3 GHz 65 W September 1, 2015 $213
6500 3.2 GHz 3.6 GHz 3.5 GHz 3.3 GHz 1050 MHz $192
6400 2.7 GHz 3.3 GHz 3.3 GHz 3.1 GHz 950 MHz $182
2 (4) Core i3 6320 3.9 GHz N/A 1150 MHz 4 MB 47 W TBD $149
6300 3.8 GHz $138
6100 3.7 GHz 1050 MHz 3 MB $117
6300T 3.3 GHz 950 MHz 4 MB 35 W September 29, 2015 $138
6100T 3.2 GHz 3 MB October 1, 2015 $117
2 (2) Pentium G4520 3.6 GHz 1050 MHz 47 W September 28, 2015 $86
G4500 3.5 GHz $75
G4400 3.4 GHz HD 510 1000 MHz TBD $64

[58]

[59]

Mobile processors[edit]

Target
Segment		 Cores
(Threads)		 Processor
Branding &
Model		 CPU
Clock
Rate		 CPU Turbo Clock Rate GPU Model GPU Clock Rate L3
cache		 Max # of PCIe Lanes TDP cTDP Release Date Price (USD)
Single Core Dual Core Quad Core Base Max Up Down
Performance 4 (8) Core i7 6920HQ 2.9 GHz 3.8 GHz 3.6 GHz 3.4 GHz HD 530 350 MHz 1050 MHz 8 MB 16 45 W N/A N/A September 1, 2015 $568
6820HQ 2.7 GHz 3.6 GHz 3.4 GHz 3.2 GHz $378
6820HK
6700HQ 2.6 GHz 3.5 GHz 3.3 GHz 3.1 GHz 6 MB
Mainstream 2 (4) 6650U 2.2 GHz 3.4 GHz 3.2 GHz N/A Iris 540 300 MHz 4 MB 12 15 W 9.5 W TBD $415
6600U 2.6 GHz HD 520 7.5 W September 1, 2015 $393
6567U 3.3 GHz 3.6 GHz 3.4 GHz Iris 550 1100 MHz 28 W 23 W TBD TBD
6560U 2.2 GHz 3.2 GHz 3.1 GHz Iris 540 1050 MHz 15 W 9.5 W
6500U 2.5 GHz 3.1 GHz 3.0 GHz HD 520 7.5W September 1, 2015 $393
4 (4) Core i5 6440HQ 2.6 GHz 3.5 GHz 3.3 GHz 3.1 GHz HD 530 350 MHz 950 MHz 6 MB 16 45 W 35 W $250
2 (4) 6360U 2.0 GHz 3.1 GHz 2.9 GHz N/A Iris 540 300 MHz 1000 MHz 4 MB 12 15 W 9.5 W TBD $304
4 (4) 6300HQ 2.3 GHz 3.2 GHz 3.0 GHz 2.8 GHz HD 530 350 MHz 950 MHz 6 MB 16 45 W 35 W September 1, 2015 $250
2 (4) 6300U 2.4 GHz 3.0 GHz 2.9 GHz N/A HD 520 300 MHz 1000 MHz 3 MB 12 15 W 7.5 W $281
6287U 3.1 GHz 3.5 GHz 3.3 GHz Iris 550 1100 MHz 4 MB 28 W 23 W TBD TBD
6267U 2.9 GHz 3.3 GHz 3.1 GHz 1050 MHz 23 W
6260U 1.8 GHz 2.9 GHz 2.7 GHz Iris 540 950 MHz 15 W 9.5 W TBD $304
6200U 2.3 GHz 2.8 GHz HD 520 1000 MHz 3 MB 7.5 W September 1, 2015 $281
Core i3 6167U 2.7 GHz 2.7 GHz Iris 550 28 W 23 W TBD TBD
6100H HD 530 350 MHz 900 MHz 35 W N/A September 1, 2015 $225
6100U 2.3 GHz 2.3 GHz 2.3 GHz HD 520 300 MHz 1000 MHz 15 W 7.5 W $281
Core m7 6Y75 1.2 GHz 3.1 GHz 2.9 GHz HD 515 300 MHz 4 MB 10 4.5 W 7 W 3.5 W $393
Core m5 6Y57 1.1 GHz 2.8 GHz 2.4 GHz 900 MHz $281
6Y54 2.7 GHz
Core m3 6Y30 0.9 GHz 2.2 GHz 2.0 GHz 850 MHz 3.8 W
Pentium 4405Y 1.5 GHz 1.5 GHz 1.5 GHz HD 510 800 MHz 2 MB 6 W N/A 4.5 W TBD $161

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