Zen+

Die shot of Ryzen 5-2600

Amd EPYC 7302 in a socket

Zen+ uses GlobalFoundries' 12 nm fabrication process,[5] an optimization of the 14 nm process used for Zen, with only minor design rule changes.[6] This means that the die sizes between Zen and Zen+ are identical as AMD chose to use the new smaller transistors to increase the amount of empty space, or "dark silicon", between the various features on the die. This was done to improve power efficiency & reduce thermal density to allow for higher clock speeds, rather than design an entirely new floorplan for a physically smaller die.[7] These process optimizations allowed 12 nm Zen+ to clock about +250 MHz (≈6%) higher, while also lowering power consumption when at the same frequency by over 10%, when compared to their prior 14 nm Zen products.[8] Although conversely at the microarchitecture level, Zen+ had only minor revisions versus Zen.[6] Known changes to the microarchitecture include improved clock speed regulation in response to workload ("Precision Boost 2"),[9] reduced cache and memory latencies (some significantly so), increased cache bandwidth, and finally improved IMC performance allowing for better DDR4 memory support (officially JEDEC rated to support up to 2933 MHz versus just 2666 MHz for Zen).[10]

Zen+ also supports improvements in the per-core clocking features, based on core utilization and CPU temperatures.[6] These changes to the core utilization, temperature, and power algorithms are branded as "Precision Boost 2" and "XFR2" ("eXtended Frequency Range 2"), evolutions of the first-generation technologies in Zen. On Zen, XFR gave an additional 50 to 200 MHz clock speed increase (in 25 MHz increments) over the maximum Precision Boost clocks. For Zen+, XFR2 is no longer listed as a separate clock modifier. Instead, the XFR temperature, power, and clock monitoring and logic feeds into the Precision Boost 2 algorithm to adjust clocks and power consumption opportunistically and dynamically.[11][12]

Ultimately, the changes in Zen+ resulted in a 3% improvement in IPC over Zen; which in conjunction with 6% higher clock speeds resulted in up to 10% overall increase in performance.[6]

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  Amd EPYC 7302 without carrier
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  Amd EPYC 7302 with carrier
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  Amd EPYC 7302 bottom side with carrier
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  Inside a Zen processor. Zen+ processors are similar.[63]

Wikimedia Commons has media related to Zen microarchitecture.

• AMD K9
• AMD K10
• Jim Keller (engineer)
• Ryzen
• Steamroller (microarchitecture)
• Zen (microarchitecture)
• Zen 2