An unreleased prototype of AMD‘s Ryzen 9 5900X3D processor for the AM4 platform has come to light.
A couple of years ago, when AMD introduced 3D V-Cache technology with the Zen 3 architecture, we ended up seeing models such as the acclaimed Ryzen 7 5800X3D in stores. However, we know that the company experimented in its labs with higher-end chips that never reached the market. Until now, information about these models pointed to configurations with double stacked memory (one 3D V-Cache chiplet on each CCD), adding up to a total of 192 MB of L3 cache.
AMD Tested Ryzen 7000X3D-Style Cache Design on an Unreleased Ryzen 9 5900X3D
The big surprise, revealed by a user on the Chinese Chiphell forum, is that a different version of this processor exists. Screenshots from tools such as CPU-Z show an engineering sample with a total of 128 MB of L3 cache, using an asymmetric 32 MB + 96 MB structure. This means AMD tested placing the extra vertical memory on only one of the two CCD blocks, a strategy identical to the one it later officially used in later generations such as the Ryzen 9 7900X3D and 7950X3D.
This 12-core and 24-thread variant appears to come from a more advanced development stage than the first prototypes. By using 3D cache on only one block, the processor was able to maintain higher clock speeds without dealing with the thermal and voltage limits of dual cache. In the leaked records, the chip reaches a boost clock between 4.65 GHz and 4.73 GHz, comfortably beating the 4.4 GHz recorded by the early 192 MB samples.
Although the Ryzen 9 5900X3D never reached store shelves, this discovery confirms that AMD came close to launching it, but that it later served as the basis for the Ryzen 7000X3D series.
