It is not possible to expand the PlayStation 5 with an M.2 SSD when the console becomes available. Sony has blocked that possibility for the time being and will release it later with an update. Sony has yet to announce which SSDs are compatible.
Sony promised at the technical presentation of its new console in March that users can add an M.2 SSD themselves, to expand the 825GB of internal storage. These are SSDs with a standard form factor, but they must meet certain requirements; the speed must, among other things, be somewhat higher than that of the internal storage.
At the time, Sony already indicated that support for fast storage expansion would probably not follow until sometime after release. Sony now confirms to The Verge that the M.2 slot has been disabled by software for the time being. The M.2 slot is easily accessible by removing the side panel from the PlayStation 5. It is not yet clear when Sony will enable the operation. About 667GB of the internal 825GB SSD is available for game storage, according to posts on Twitter.
The internal PCIe 4.0 ssd of the PlayStation 5 has a throughput speed of 5.5 GB / s. There are also M.2 SSDs for sale that are just as fast or faster, such as the Samsung 980 Pro and the WD Black SN850. Western Digital claimed when the SSDs were introduced that they are suitable for the PlayStation 5, but Sony has not confirmed that. How Sony will certify SSDs for the PlayStation 5 is not yet clear. In theory, the manufacturer can limit via firmware which SSDs work in the console.
Only expanding the fast internal storage is not possible initially. Users can connect an external HDD or SSD via USB. However, such storage is not suitable for next-gen games. The Xbox Series X can already be expanded with 1TB of extra storage that is just as fast as the internal SSD. However, Microsoft uses a proprietary format and so far only Seagate has released an SSD that is suitable for this.
M.2 slot in PlayStation 5