Edit 8/25/2021 7pm pt: Correction made to reflect that the chips are predicted to use 3D V-Cache, not HBM.
Original Article: AMD released the EPYC 7003-series (Milan) processors for data centers a little over a year ago. However, the chipmaker is reportedly preparing a Milan overhaul that features 3D die stacking.
Hardware leakers ExecutableFix and Patrick Schur gave rise to the rumor that AMD will implement its chip stacking tech with Milan-X. In terms of design, Milan-X retains the Zen 3 CPU cores and will probably max out at 64 cores, just like the vanilla Milan chips. The whole point behind X3D is the ability to deliver more bandwidth, therefore, Milan-X will likely sport stacked memory dies.
It's still unknown what kind of memory AMD will stack on Milan-X. However, the general consensus is that AMD will tap its new 3D V-Cache technology. This technique, as AMD demoed earlier this year, enables stacking an additional SRAM onto the chip to boost L3 capacity. We don't know exactly how much bandwidth or capacity since AMD hasn't revealed the design to the public yet.
AMD EPYC Milan-X Specifications*
|Processor||Cores / Threads||OPN|
|EPYC 7773X||64 / 128||100-000000504|
|EPYC 7573X||32 / 64||100-000000506|
|EPYC 7473X||24 / 48||100-000000507|
|EPYC 7373X||16 / 32||100-000000508|
*Specifications are unconfirmed.
Hardware detective momomo_us has purportedly uncovered the specifications for Milan-X. The OPNs (Ordering Part Numbers) can be found in AMD's Product Master document, so we know that the product numbers are at least legit, though the jury is still out about whether they match the upcoming Milan-X variants. According to leaked information, Milan-X will in all likelihood launch under the EPYC 7073-series branding, which makes sense since Milan debuted under the 7003-series moniker.
The EPYC 7773X appears to be the flagship SKU for the Milan-X lineup. It's likely the Milan-X counterpart for the existing EPYC 7763. Therefore, the EPYC 7573X, 7473X and 7373X are probably equivalent to the EPYC 7543, 7443 and 7343, respectively. As per momomo_us' tip, Milan-X and Milan share the same core configurations as previously speculated. The clock speeds, on the other hand, remain a mystery. We did notice that there weren't any mentions of the 56-core, 48-core, 28-core or 8-core models for Milan-X. Nevertheless, it's plausible that momomo_us hasn't found them yet, or that AMD is merely strategically targeting certain price bands for what will likely be very pricey high-performance chips.
Given the design, Milan-X may be a stopgap response to Intel's forthcoming Sapphire Rapids with HBM memory. EPYC Genoa is AMD's hard hitter and the true rival to Sapphires Rapid. However, Genoa isn't expected to arrive until 2022.