Zen (microarchitecture)

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Zen is the codename for a family of computer processor microarchitectures from AMD, first launched in February 2017 with the first generation of its Ryzen CPUs. It is used in Ryzen (desktop and mobile), Ryzen Threadripper (workstation/high end desktop), and Epyc (server).


Microarchitecture Zen[1] Zen 2[2] Zen 3[3] Zen 3+
Microarchitecture variants Zen Zen+
Fabrication process (nm) 14nm 12 nm 7nm 6nm
Cache µop 2K 4K
L1 Data Size 32 KiB
Ways 4 8
Latency 4-8
Instruction Size 64 KiB 32 KiB
Ways 8
Latency ? 4-8
TLB 512-entry 1024-entry
L2 Size 512 KiB/core
Ways 8
Latency 17 12
TLB 1536-entry 2048-entry
L3 Size 2048 KiB/core 4096 KiB/core 4096 KiB/core
Ways 16[4]
Latency 35 40 46
Max CPU core 32 64 8
Simultaneous multithreading (SMT) Yes
OoO window (ROB) 192 224 256
Pipeline stage 19
Decode (ways) 4 6[5]
Scheduler Entries ?
Dispatch 6
Register file Integer 84 92 96
Floating-point 96
Queue Instruction 72
Allocation 44
AGUs 2 3


Zen with and with out GPU
Ryzen Epyc MCM
Ryzen ThreadRipper MCM

First generation[edit]

The first generation Zen was launched with the Ryzen 1000 series of CPUs (codenamed Summit Ridge) in February 2017.[6] The first Zen-based preview system was demonstrated at E3 2016, and first substantially detailed at an event hosted a block away from the Intel Developer Forum 2016. The first Zen-based CPUs reached the market in early March 2017, and Zen-derived Epyc server processors (codenamed "Naples") launched in June 2017[7] and Zen-based APUs (codenamed "Raven Ridge") arrived in November 2017.[8] This first iteration of Zen utilized Global Foundries' 14 nm manufacturing process.[9]

Second generation[edit]

Zen+ was first released in April 2018,[10] powering the second generation of Ryzen processors, known as Ryzen 2000 (codenamed "Pinnacle Ridge") for mainstream desktop systems, and Threadripper 2000 (codenamed "Colfax") for high-end desktop setups. This generation used Global Foundries' 12 nm process, an enhanced version of their 14 nm node.[11][12]

Third generation[edit]

The Ryzen 3000 series CPUs were released on July 7, 2019,[13][14] while the Zen 2-based Epyc server CPUs (codename "Rome") were released on August 7, 2019.[15] Zen 2 also powered a line of desktop APUs marketed as Ryzen 4000. These were the first consumer CPUs using TSMC's 7 nm process node.[16] Zen 2 introduced the chiplet based architecture, where all desktop, workstation and server CPUs utilized the same core chiplets[citation needed]. The IO for these processors was taken care of by an IO die,[17] separate from the processing cores. The IO die used by Matisse processors was a small chip on GF 12 nm,[18] where as the IO die utilized for Threadripper and Epyc was much larger, able to handle more IO.[18] These chiplets were linked by AMD's own second generation Infinity Fabric,[18] allowing a low-latency interconnect between the cores and their IO. Matisse was limited to two 8-core chiplets and Threadripper/Epyc was limited to eight 8-core chiplets. The processing cores in the chiplets were organized in CCXs (Core Complexes) of four cores, linked together to form a single eight core CCD (Core Chiplet Die).[19]

Fourth generation[edit]

Zen 3 was released on November 5, 2020,[20] using a more matured 7 nm manufacturing process, powering Ryzen 5000 series CPUs & APUs[20] (codename "Vermeer" (CPU) and "Cézanne" (APU)) and Epyc processors (codename "Milan"). Zen 3's main performance gain over Zen 2 is the introduction of a unified CCX, which means that each core chiplet is now composed of eight cores with access to 32MB of cache, instead of two sets of four cores with access to 16MB of cache each.[21]

Zen 3D was officially previewed on May 31, 2021 and confirmed for release in the first half of 2022 in AMD's Computex 2021 presentation. Zen 3D will differ from Zen 3 in that it will include V-cache, 3D-stacked L4 cache. This added cache should bring a 15% performance increase in gaming applications on average.[22]

Zen 3D for server, codenamed Milan-X was announced in Nov 8th 2021's AMD Accelerated Data Center Premiere Keynote. It should bring a 50% increase in select datacenter applications over Zen 3's Milan CPUs while maintaining socket compatibility with them.[23]

Fifth generation[edit]

Epyc server CPUs with Zen 4, codenamed Genoa, were officially unveiled at AMD's Accelerated Data Center Premiere Keynote on Nov 8th 2021. They will have up to 96 Zen 4 cores and will support both PCIE 5.0 and DDR5.

Furthermore, Zen 4 Cloud (a variant of Zen 4), abbreviated to Zen 4c and codenamed Bergamo, was also announced. Zen 4c is designed to have significantly greater density than standard Zen4 while delivering greater power efficiency. This is achieved by redesigning Zen4's cache (presumably removing a certain amount of L2 and L3 cache) to maximise density and compute throughput. Bergamo will have up to 128 Zen 4c cores and will be socket-compatible with Genoa.

Both Zen 4 and Zen 4 Cloud will be manufactured on a non-specified variety of TSMC 5 nm and are slated to launch in 2022.[23]

In addition to the Epyc 7004 server processors (Genoa and Bergamo), in May of 2022 AMD's roadmap showed that Zen 4 will power Ryzen 7000 mainstream desktop processors (codenamed "Raphael"), high-end mobile processors (codenamed "Dragon Range"), thin & light mobile processors (codenamed "Phoenix").[24][25][26]

Sixth generation[edit]

Zen 5 was shown on AMD's Zen roadmap in May 2022.[24] It is believed to use TSMC's 3 nm process.[27] It will power Ryzen 8000 mainstream desktop processors (codenamed "Granite Ridge"), high-end mobile processors (codenamed "Strix Point"), and Epyc 7005 server processors (codenamed "Turin").

See also[edit]


  1. ^ "Zen - Microarchitectures - AMD - WikiChip". en.wikichip.org. Retrieved September 16, 2021.
  2. ^ "Zen 2 - Microarchitectures - AMD - WikiChip". en.wikichip.org. Retrieved September 16, 2021.
  3. ^ "Zen 3 - Microarchitectures - AMD - WikiChip". en.wikichip.org. Retrieved September 16, 2021.
  4. ^ "AMD Ryzen 7 5800H Mobile processor - 100-000000295". www.cpu-world.com. Retrieved September 17, 2021.
  5. ^ Frumusanu, Dr Ian Cutress, Andrei. "AMD Zen 3 Ryzen Deep Dive Review: 5950X, 5900X, 5800X and 5600X Tested". www.anandtech.com. Retrieved November 15, 2021.
  6. ^ Anthony, Sebastian (August 18, 2016). "AMD says Zen CPU will outperform Intel Broadwell-E, delays release to 2017". Ars Technica. Retrieved August 18, 2016.{{cite news}}: CS1 maint: url-status (link)
  7. ^ Cutress, Ian (June 20, 2017). "AMD's Future in Servers: New 7000-Series CPUs Launched and EPYC Analysis". AnandTech. Retrieved August 8, 2017.{{cite web}}: CS1 maint: url-status (link)
  8. ^ "HP ENVY x360 Convertible Laptop - 15z touch - HP® Official Store". store.hp.com.
  9. ^ Lilly, Paul (July 23, 2016). "AMD Shipping Zen In Limited Quantity Q4, Volume Rollout Ramps Q1 2017". HotHardware. Archived from the original on April 21, 2019. Retrieved October 21, 2020.
  10. ^ Bright, Peter (January 8, 2018). "AMD's 2018 roadmap: Desktop APUs in February, second-generation Ryzen in April". Ars Technica. Retrieved January 9, 2018.
  11. ^ Cutress, Ian. "The AMD 2nd Gen Ryzen Deep Dive: The 2700X, 2700, 2600X, and 2600 Tested". www.anandtech.com. Retrieved October 21, 2020.
  12. ^ Hruska, Joel (September 22, 2017). "AMD Will Use 'New' GlobalFoundries 12nm Node for Future CPUs, GPUs - ExtremeTech". www.extremetech.com. Retrieved October 21, 2020.
  13. ^ Leather, Antony. "AMD Ryzen 9 3900X and Ryzen 7 3700X Review: Old Ryzen Owners Look Away Now". Forbes. Retrieved September 19, 2019.
  14. ^ "AMD Ryzen 3000 CPUs launching July 7 with up to 12 cores". PCGamesN. Retrieved May 28, 2019.
  15. ^ "2nd Gen AMD EPYC™ Processors Set New Standard for the Modern Datacenter with Record-Breaking Performance and Significant TCO Savings". AMD. August 7, 2019. Retrieved August 8, 2019.
  16. ^ January 2020, Bill Thomas 15. "AMD Zen 2 specs, price and release date: all about AMD's newest processor tech". TechRadar. Retrieved October 21, 2020.
  17. ^ Jun 12th, btarunr; Discuss, 2019 23:24. "AMD Ryzen 3000 "Matisse" I/O Controller Die 12nm, Not 14nm". TechPowerUp. Retrieved October 21, 2020.{{cite web}}: CS1 maint: numeric names: authors list (link)
  18. ^ a b c Cutress, Ian (June 10, 2019). "AMD Zen 2 Microarchitecture Analysis: Ryzen 3000 and EPYC Rome". AnandTech. Retrieved October 21, 2020.{{cite web}}: CS1 maint: url-status (link)
  19. ^ September 2019, Scharon Harding 14. "What Is an AMD CCX? A Basic Definition". Tom's Hardware. Retrieved October 21, 2020.
  20. ^ a b Ridley, Jacob (October 8, 2020). "AMD Ryzen 5000 – Zen 3 CPU release date, specs, pricing, and performance". PC Gamer. Retrieved October 20, 2020.
  21. ^ "AMD's Zen 3 Drops November 5 With Major IPC Enhancements - ExtremeTech". www.extremetech.com. Retrieved October 21, 2020.
  22. ^ AMD at Computex 2021, retrieved November 15, 2021
  23. ^ a b AMD Accelerated Data Center Premiere Keynote, retrieved November 15, 2021
  24. ^ a b "AMD confirms Zen4 & Ryzen 7000 series lineup: Raphael in 2022, Dragon Range and Phoenix in 2023". videocardz.com. May 3, 2022.
  25. ^ Zhiye Liu (May 3, 2022). "AMD Confirms Zen 4 Dragon Range, Phoenix APUs for 2023". tomshardware.com.
  26. ^ Anthony Garreffa (May 3, 2022). "AMD confirms Ryzen 7000 series CPUs this year: Zen 4 + DDR5 + PCIe 5.0". tweaktown.com.
  27. ^ Hassan Mujtaba (May 1, 2022). "AMD Zen 5 CPUs Might Get Delayed To 2024-2025 Due To TSMC's Priority Allocation of 3nm Node To Intel & Apple Zen 5". wccftech.com.