The PS5's SSD may only have 660GB of usable space after formatting and reserved OS storage, recent leaks indicate.
If these Russian leaks are accurate, the PS5's internal PCIe 4.0 SSD may fill up fast. The console comes with an ultra-fast SSD that's capable of hitting 5.5GB/sec uncompressed data transfer speeds, but the capacity has been reduced to save on MSRP costs. The PS5's internal storage only cocks in at 825GB, which is just 768GB after formatting. This useable space is further reduced by reserved data for the operating system and other features like quick resume.
Now we have an idea of the PS5's real-world storage capacity. According to new unverified leaks, the PS5 has roughly 660GB of available space for games, content and media. This includes the pre-installed Astro's Playroom, which is reportedly 2.4GB. This means the console reserves roughly 128GB for the OS and other data processing features, and possibly indicates the PS5's built-in NVMe is also used as a virtual RAM buffer to help massive accelerate and efficiently process data and textures.
This info could be faked though. It's based on a very blurry screenshot circulated from a PS5 devkit (hence the black controller). It does match up with the reserved space in the Xbox Series X, though. Despite the speed and capacity differences, both SSDs operate on a similar level--they're powered by different feature sets and APIs, but ultimately share the similar x86 architectural format and will be somewhat standardized for third-party games.
So it makes sense for both the PS5 and Series X to reserve roughly the same storage ratio for OS and other next-gen features. Remember that the PCIe 4.0 SSDs are the heart of making next-gen performance possible, and that requires some extra space for caching and critical OS feature sets.
The PlayStation 5 releases November 12, 2020 for $499 (the disc-free version is $399. Check below for a side-by-side comparison of the full next-generation of console hardware: