AMD Unveils Final 4th Gen Epyc CPU Code-Named Siena

AMD has announced the final CPU in its 4th generation lineup of Zen 4 processors for the data center with its new Siena line of 8004 CPUs. This lineup will occupy the bottom rung on the performance ladder in exchange for maximum efficiency, as it's designed for smaller deployments where cost and square footage are paramount concerns. The addition of Siena to the Epyc lineup plugs a big hole in the lineup, as all the previous processors were designed for either maximum performance or maximum thread counts. Siena tops out at just 64 cores and exclusively uses the company's efficiency-focused Zen 4c cores.

To quickly recap, the 4th gen Epyc family includes four CPU lineups. There's Genoa, which is the "standard" server CPU with 96 Zen 4 cores. Then there's the Genoa-X, which is Genoa but with V-Cache for 1.1GB of L3 cache. For workloads where maximum core count is required, there's Bergamo, which has 128 Zen 4c cores for 256 threads. Then there's the new kid, Siena, which offers "balanced performance" along with superior performance-per-watt compared to its competitors. AMD is targeting cloud service, intelligent edge, and telcos with Siena.

AMD has taken quite a different route compared to Intel when it comes to ifs efficiency-focused Zen 4c cores, endowing them with the same IPC and instruction set as regular Zen 4. Credit: AMD

Siena is a slimmed-down version of Bergamo and eschews that chip's SP5 socket for the SP6 variety, which is a bit smaller and made for more compact installation. TDP for the family ranges from a lithe 70W up to 225W, as opposed to 400W for Genoa chips, so efficiency is king with this lineup. They also offer half the memory bandwidth with support for six channels of DDR5-4800 compared with Genoa's 12 lanes. When using 96GB DIMMs per channel, it supports up to 1.152TB of ECC memory. PCI Express lanes are also reduced from 128 lanes with two sockets possible to 96 lanes with only one socket supported.

AMD has three OEM systems ready to go, spanning workloads from health care to AI. Credit: AMD

The Siena family will offer six SKUs ranging from 64 cores down to just eight with a single CCD. The eight-core chips sport a maximum TDP of just 90W, which sounds kind of cute. The company has already prepped three OEM example products with its 8004 chip from Lenovo, Dell, and SuperMicro, and each one looks nothing like the other (above). AMD hopes to capitalize on the market for smaller, quieter, more efficient servers serving various markets that require just a single socket.