AMD EPYC Bergamo CPU Die Detailed: 16 Zen 4C “Vindhya” Cores Per CCD & 35% Smaller Core Area

More details of AMD's upcoming EPYC Bergamo CPUs which will be powered by the new Zen 4C Dense cores have been revealed by Semianalysis.

The AMD EPYC Bergamo CPU lineup is expected to launch next week at the “AMD Data Center and AI Technology Premiere" where the company is going to talk about its server, cloud, and AI product families. AMD will go into detail for multiple products which include the first products based on the Zen 4C or any Zen-Dense design, Bergamo. Being part of the same EPYC 9004 family, the Bergamo chips might look similar but inside their heart, they are a very different kind of beast that target a very specific set of applications.

The main competition of AMD's EPYC Bergamo is the various Arm & compute-density optimized chips coming from Intel such as Sierra Forest which is going to feature up to 144 E-Cores. Intel's solution won't be out till the first half of 2024 and that is if everything goes according to plan for Intel 4 (process node). This will also be targeted as the competitor to NVIDIA's Grace which relies purely on Arm cores and among a dozen of other Arm-based chips that are becoming a common household in major tech data centers.

So what we already know about AMD's EPYC Bergamo CPUs is that they will feature up to 128 cores based on the Zen 4C cores which are fabricated on TSMC's 4nm process node which can be seen as a slight improvement over the 5nm process node which powers the Zen 4 cores at the moment. It's going to offer up to 256 threads so multi-threading is there whereas that's not the case with Intel's E-Cores, it supports 12-channel DDR5 memory, PCIe Gen 5.0 functionality, & is drop-in compatible with the existing SP5 socket with no software port required since the same Zen 4 ISA is used.

But Dylan Patel of Semianalysis provides a more deep-dive into the architectural side of things and offers specifications of two of the CPUs that will be launching this month, the EPYC 9754 with 128 & EPYC 9734 with 112 cores. The specs are pretty much identical to what was leaked earlier but the clock speeds have been changed due to the difference in ES clocks from a year ago and retail clocks from now.

But the more juicy details aren't the specifications of the chips but the core configurations and the core details. It is stated that the Bergamo chips make use of eight Zen 4C CCDs which include up to 16 Zen 4C cores. Each CCD comprises two CCX's which feature 8 cores each and each CCX has a shared 16 MB L3 cache. So we are seeing the return of the dual-CCX portioning for Zen 4C versus the singular unified CCD/CCX we have seen since Zen 3.

AMD managed to fit twice the number of cores and threads with the same L3 cache within a die size that's under 10% bigger than the Zen 4 CCD (72.7mm2 vs 66.3mm2). The Zen 4C CCD which is codenamed "Dinoysus" has an overall -35.4% lower core area and almost every aspect of the CCD has been reduced by -35% to -45%. You can see the core area breakdown and size comparisons of the Zen 4C and Zen 4 core dies below:

Considering that AMD used a 8 CCD package for its EPYC Bergamo CPUs, it might be possible that a 12 CCD package could've been tested or may have been kept in wraps for a future release. This can offer up to 192 cores and 384 threads which will be something to boast about but considering that Intel is not getting close to 192 cores this early, it might be better to just wait and release it a better time. Overall, AMD's position in the dense cloud market will be solidified with its Zen 4C and future Zen 5C/6C cores which are expected to launch in the coming years.