Sony's requirements, in plain English
Sony's official requirements for the PS5 M.2 expansion slot are specific. The drive must be an M.2 NVMe SSD on a PCIe Gen 4 x4 interface, between 250GB and 8TB, in one of the 2230, 2242, 2260, 2280 or 22110 sizes. Sony recommends a sequential read speed of 5,500 MB/s or faster, which is why every drive in the table above meets that bar.
The drive also needs a cooling structure, such as a heatsink or heat transfer sheet, and the whole assembly must fit within 25mm wide and 11.25mm thick (up to 8.0mm above the board and 2.45mm below). Most drives sold as PS5-ready include a slim heatsink that fits; if you buy a bare drive, add a low-profile heatsink that stays within those limits.
Does a faster SSD make PS5 games load faster?
Only up to a point. The PS5 console storage is already very fast, and games are designed around it, so any drive that meets Sony's 5,500 MB/s recommendation loads games at a similar speed. A PCIe 5.0 drive such as the Samsung 9100 Pro works in the PS5 slot, but it runs at PCIe 4.0 speed there, so you pay for performance the console cannot use.
For PS5 buyers, capacity and a reliable brand matter more than chasing the highest read speed. The Samsung 990 Pro, Kingston Fury Renegade and Seagate FireCuda 530 all clear the speed recommendation comfortably and carry five-year warranties.
How much extra storage to buy
PS5 games are large, and many take 50 to 100GB each once installed. A 1TB expansion drive holds a good handful of big titles on top of what already fits on the console. 2TB is the sensible choice if you keep a large library installed, and 4TB suits anyone who never wants to delete a game again.
An external USB drive is a cheaper way to store games you are not playing, but Sony only lets you play PS5 games from console storage or an M.2 SSD. Games on USB storage have to be copied back before you can play them, so the M.2 slot is the one that actually adds playable space.