RAM disk on Ryzen’s 3D V-Cache reaches insane speeds

Fast SSDs in all their glory – the fastest form of storage has always been RAM disks. The areas of use for these have not been that many in recent years, with use in servers that have no permanent storage but load the operating system from a memory card or similar directly to a RAM disk and then reside entirely in the working memory.

The fact that it is not so common does not prevent users from experimenting with the technology, and this applies not only to RAM disks in the computer’s normal working memory, but nowadays also to the processor’s built-in cache memory. Tom’s Hardware reports how the account Felt back in February, X shared instructions for placing a RAM disk on the Ryzen 7 5800X3D’s 3D V‑Cache, with astonishing results. In Crystaldiskmark, it provides read and write speeds of 183 and 175 GB/s respectively. That’s about 15 times faster than SSDs with PCI-Express 5.0. Similar results have also been achieved with the Ryzen 7 7800X3D, among others.

The technician uses the Osfmount program to create the RAM disk, with very specific settings to be able to run Crystaldiskmark and achieve the high speeds. The file system is FAT32 and Crystaldiskmark should be set to run SEQ256K Q1T16 with zeros instead of random data.

Tom’s Hardware points out that this type of RAM disk is not useful in practice, but rather an interesting experiment that explores the theoretical possibilities of 3D V‑Cache. However, if AMD came up with a more reliable method, it could possibly be more useful, especially on EPYC and Threadripper processors that have significantly more of the fast cache memory.