After a busy day of product announcements and updates for AMD’s Data Center Business Group, AMD finally unveiled its highly anticipated high-density ‘Bergamo’ server CPUs this morning. Based on AMD’s density-optimized Zen 4c architecture, the new EPYC 97×4 chips offer up to 128 CPU cores. That’s 32 more cores than AMD’s current-generation flagship EPYC 9004 ‘Genoa’ chip. According to AMD, the new EPYC processors are shipping now, but we’re still waiting for details on their actual availability.
AMD teased the Bergamo and Zen 4c architectures for the first time over 18 months ago, outlining plans to offer high-density EPYC CPUs specifically designed for the cloud computing market. The Zen 4c cores will use his ISA which is the same as AMD’s regular Zen 4 architecture and both architecture sets will be fully ISA compatible but that feature will come in a denser design. Ultimately, while AMD’s mainline Zen 4 EPYC chips are designed to balance performance and density, these Zen 4c EPYC chips focus purely on density, maximizing the number of vCPUs. Increase the total number of CPU cores available in your market. Can run on a single physical CPU.
We’re waiting for more details on the Zen 4c architecture itself, but for now we know that AMD is taking some steps to increase CPU core density. This includes redesigning the architectural layout to favor density over clock speed (higher clock speed circuits are a trade-off for density and vice versa), or increasing the number of caches per CPU core. This includes reducing volume. AMD has also packed more CPU cores entirely within each Core Complex Die (CCD). Zen 4 has 8 cores per CCD, while Zen 4c will have 16 cores per CCD. Interestingly, this means that the Zen 4c EPYC chip has fewer CCDs overall than the original Zen 4 chip.
Despite these density-focused improvements, the Bergamo is still a big chip overall in terms of the total number of transistors used. The fully kitted chip consists of 82B transistors compared to about 90B of the full Genoa chip. Considering the high number of CPU cores available in Bergamo, this means that a single Zen 4c core would be about 68% of the transistor count as a Zen 4 core when amortized in terms of transistors across the chip. Become. In practice, the savings at the CPU core level alone aren’t likely to be that big, but this shows how much AMD was able to save in transistor count by cutting everything but the CPU cores. I’m here.
On the other hand, since they are a subset of the EPYC 9004 series, the 97×4 EPYC chips are socket compatible with the rest of the 9004 family using the same SP5 socket. Of course, using this chip requires a BIOS update, but server vendors can incorporate the chip into their existing designs.
As mentioned earlier, the primary market for the EPUC 97×4 family is the cloud computing market. According to AMD, the ‘c’ in Zen 4c stands for ‘cloud’. With higher core counts and not-so-high clock speeds, the resulting chip is more energy efficient per core than the Genoa design. Given that power is one of the biggest ongoing costs for AMD’s target market, which is a bigger consideration. As part of today’s presentation, AMD is touting a 2.7x improvement in energy efficiency, but it’s unclear how this number compares.
AMD is specifically looking to compete with its Arm-based rivals in this space with higher core density and enhanced energy efficiency, with the likes of Ampere and Amazon using Arm architecture cores to produce 128 (or more). cores on a single chip. AMD will eventually fend off Intel in this area as well, but not until 2024 Sierra Forest.
Pure computing users should also keep an eye on these new Bergamo chips, as higher core counts change the current performance calculations a bit. In terms of pure computational throughput, the new chip theoretically offers better performance than the 96-core Genoa chip, as the additional 32 CPU cores more than make up for the loss in clock speed. That said, server CPU caches and other supporting hardware improve performance in other ways, so performance calculations are rarely this straightforward for real-world workloads. Still, if you just want a bunch of semi-independent threads to rip, Bergamo might offer some surprises.
In the next few days and weeks we will be sharing more details about the EPYC 97×4 series chips, including details about the Zen 4c core architecture as AMD releases more information about it. Until then, please look forward to it.
