AMD EPYC "Bergamo" Uses 16-core Zen 4c CCDs, Barely 10% Larger than Regular Zen 4 CCDs
A SemiAnalysis report sheds light on just how much smaller the "Zen 4c" CPU core is compared to the regular "Zen 4." AMD's upcoming high core-count enterprise processor for cloud data-center deployments, the EPYC "Bergamo," is based on the new "Zen 4c" microarchitecture. Although with the same ISA as "Zen 4," the "Zen 4c" is essentially a low-power, lite version of the core, with significantly higher performance/Watt. The core is physically smaller than a regular "Zen 4" core, which allows AMD to create CCDs (CPU core dies) with 16 cores, compared to the current "Zen 4" CCD with 8.
The 16-core "Zen 4c" CCD is built on the same 5 nm EUV foundry node as the 8-core "Zen 4" CCD, and internally features two CCX (CPU core complex), each with 8 "Zen 4c" cores. Each of the two CCX shares a 16 MB L3 cache among the cores. The SemiAnalysis report states that the dedicated L2 cache size of the "Zen 4c" core remains at 1 MB, just like that of the regular "Zen 4." Perhaps the biggest finding is their die-size estimation, which puts the 16-core "Zen 4c" CCD just 9.6% larger in die-area, than the 8-core "Zen 4" CCD. That's 72.7 mm² per CCD, compared to 66.3 mm² of the regular 8-core "Zen 4" CCD.
The 16-core "Zen 4c" CCD is built on the same 5 nm EUV foundry node as the 8-core "Zen 4" CCD, and internally features two CCX (CPU core complex), each with 8 "Zen 4c" cores. Each of the two CCX shares a 16 MB L3 cache among the cores. The SemiAnalysis report states that the dedicated L2 cache size of the "Zen 4c" core remains at 1 MB, just like that of the regular "Zen 4." Perhaps the biggest finding is their die-size estimation, which puts the 16-core "Zen 4c" CCD just 9.6% larger in die-area, than the 8-core "Zen 4" CCD. That's 72.7 mm² per CCD, compared to 66.3 mm² of the regular 8-core "Zen 4" CCD.