An engineering sample of AMD's never-released Ryzen 9 5900X3D has surfaced on the Chinese forum Chiphell, and it looks quite different from the prototype AMD has shown before. The 12-core, 24-thread Zen 3 chip carries the code 100-000000652 and reports 128 MB of L3 cache, split as 96 MB on one CCD and 32 MB on the other. That means only one of its two six-core chiplets has the 64 MB 3D V-Cache stack.
The Ryzen 9 5900X3D and 5950X3D prototypes that AMD showed to Gamers Nexus in 2023 had cache stacked on both CCDs, for 192 MB in total. The single-stack layout apparently lets the chip clock higher. CPU-Z screenshots from the owner show it running at around 4.7 GHz with a 105 W TDP, while the dual-stack 5900X3D topped out at a 4.4 GHz boost.
Getting it to boot took some effort, though. The sample reportedly refuses to work on current BIOS versions and only started with an older one carrying SMU firmware 56.70.0. The owner has apparently asked ASRock to add support in a newer BIOS. At retail, the Zen 3 X3D lineup started with the eight-core Ryzen 7 5800X3D in 2022 and never included a dual-CCD chip.
Interestingly, the one-CCD approach seen here is the same one AMD later used for its Ryzen 9 X3D chips on AM5, before the Ryzen 9 9950X3D2 Dual Edition put cache on both chiplets this year. AMD hasn't confirmed anything about this sample, of course, but it's interesting to see from an archival standpoint.
Source: TechPowerUp News · Summarized by HeadlinesBriefing