AMD reveals details on upcoming Zen 3 "Milan" and Zen 4 "Genoa" EPYC server CPU architectures

AMD is hitting hard in the server space. The release of its Zen 2-based EPYC server CPUs (codenamed Rome) was a major blow to Intel’s enterprise business as Team Red’s chips have proven themselves to be competitive (or better) alternatives to Intel’s incumbent ICs. It doesn’t look like AMD is slowing down, either. Zen 3 and Zen 4 server CPUs are on their way over the next few years; the new silicon looks like it will continue to pressure and steal market share from Intel.

AMD showed off its EPYC roadmap at the HPC-AI Advisory Council UK conference this past weekend and revealed a few details about the Zen 3 (“Milan”) and Zen 4 (“Genoa”) EPYC CPUs. Milan is set to release sometime in 2020 and seems more like a refinement of Rome than anything else. Although it retains many of the same features of Rome, Milan will be built on AMD’s new 7nm+ node process, which should increase performance with some slight improvements to energy efficiency. Milan will keep the same 64 core maximum as Rome and will be compatible with the SP3 socket. Somewhat disappointing is confirmation that Milan CPUs will have only two threads per core, counter to earlier rumors of SMT4 (four threads per core) showing up as early as Milan.

Perhaps most interestingly is a tweak to the cache arrangement. Rome splits the CPU’s chiplets into two groups of four cores (called a Compute Complex, or CCX) and gives each group a shared 16 MB of L3 cache, Milan will keep the eight cores of each chiplet grouped together. The eight cores will share 32 MB or more of L3 cache.

Moving down the road, Zen 4 EPYC CPUs, dubbed “Genoa,” should drop in 2021. Genoa will use a new SP5 socket and brings with it support for a bevy of new features. Chief among these is possible support for DDR5 RAM and PCIe 5.0. AMD is still in the “definition” phase for Genoa, so not a lot has been pinned down. Rumors that Genoa will be built on a 5nm or 6nm process are flying, but this is wild speculation at this point.

EPYC has been a game-changer in the enterprise market. Intel has long stood in dominance over all other companies, but AMD came out swinging with Zen. It looks like AMD will be going for a knockout over the next two years, but Intel is sure to defend and counter with something spectacular. The server CPU industry hasn’t been this exciting for a while.