AMD 3D V-Cache Tests Reveal Minimal Latency Increase, Improved Bandwidth


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Aug 17, 2014
Chips and Cheese have tested the latency of AMD's EPYC 7V73X (Milan-X) processor with 3D V-Cache. It's the same technology coming to mainstream Ryzen processors, so the results probably foreshadow the gains we can expect from the chips, such as the Ryzen 7 5800X3D.

The rest results from Chips and Cheese revealed that 3D V-Cache has minimal impact on cache and memory latency. According to the EPYC 7V73X data, the increase resulted in three to four cycles of extra latency. That's very impressive, considering that the EPYC 7V73X (768MB) sports up to three times more L3 cache than the EPYC 7763 (256MB). The publication also noted that while Milan-X has lower clock speeds than Milan, the former boosts better, negating the latency increase from 3D V-Cache.

AMD's 3D V-Cache, which has been in development for years, allows the chipmaker to stack more L3 cache on its Zen 3 processors. The chipmaker fuses the 3D V-Cache chiplet to the top of the core complex die (CCD) through a hybrid bonding process. As a result, AMD can implement a single layer of stacked L3 cache on its Ryzen processors in its current stage. However, the technology enables up to multiple dies, so future consumer Ryzen processors could potentially arrive with vast amounts of L3 cache.