You can buy a PCIe card for mounting SATA devices such as an SSD. How does this compare to purchasing a M.2 SSD as an alternative?
I PCIe card with a SATA controller is just that. One site a PCI-e interface with bandwith depending on the PCI-e version and width, and on the other side connectors for SATA devices. The SATA protocol is made for high latency devices and is not optimal for SSDs. It also maxed out at 6Gbit/sec.
A M2 SSD can be connected either via:
- A SATA link to the M2 socket.
- A direct PCI-e link, up to x4, with PCI-e v2 or v3.
If #1 is used there is no real difference other than the need for a PCI-e SATA card and the form factor differences (most SATA SSDa are 2½ inch like a laptop HDD. Need a data cable and a power cable). A M2 is much smaller.
If #2 is used bandwidth is much much higher (which is nice) and the NVME protocol will be used. The latter is specifically designed for low latency devices like SSDs and much more efficient.
Thus if you have any choice going for M2 with NVME always trumps on performance.
To confuse things: there are also PCI-e cards with an M2 interface in it. Think of these are a more 'plug' to convert the connector type. I assumed you did not mean these. If you did, then please edit your post.