AMD Details its 3D V-Cache Design at ISSCC



AMD Details its 3D V-Cache Design at ISSCC

This week, the International Solid-State Circuits Conference is taking place online and during one of the sessions, AMD shared some more details of its 3D V-Cache design. The interesting part here is the overall design of AMD's 3D V-Cache, as well as how it interfaces with its CPU dies. The cache chip itself is said to measure 36 mm² and interfaces directly with the L3 cache using a Through Silicon Via or TSV interface. For all the CPU cores to be able to communicate with the 3D V-Cache, AMD has implemented a shared ring bus design at the L3 level. The entire L3 cache is said to be available to each of the cores, which should further help improve performance.

The 3D V-Cache is made up of multiple 8 MB "slices" which has a 1,024 contact interface with a single CPU core, for a total of 8,192 connections in total between the CCX and the 3D V-Cache. This allows for a bandwidth in excess of two terabyte per second, per slice, in full duplex mode. This should allow for full L3 speeds for the 3D V-Cache, despite the fact that it's not an integrated part of the CCX. AMD is also said to have improved the design of its CCX for the upcoming Ryzen 7 5800X3D in several ways to try and reduce the power draw, while improving clock speeds. AMD has yet to reveal a launch date for the Ryzen 7 5800X3D, but it'll be interesting to see if the 3D V-Cache and the various minor optimizations can make it competitive with Intel's Alder Lake CPUs until Zen 4 arrives.

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