M.2 SSD compatibility with my laptop

Question

I have a ThinkPad P50 and I am planning to buy and install an M.2 SSD on it.

The laptop has two built-in M.2 SSD slots.

• M.2 SSD slot #1: The laptop came with an M.2 SSD with the OS installed on it.
• M.2 SSD slot #2: I am planning to buy and install a Samsung 850 EVO 1TB - M.2 SATA III Internal SSD (MZ-N5E1T0BW) (http://a.co/6SJ5ZyY)

I have installed lots of IDE or SATA drives on laptops in past 20 years. SATA drives are quite easy to install and I have not had any compatibility issue with a SATA drive.

I have been installing and using Samsung SSD SATA drives with no issue, and they have been compatible with all PCs or laptops I had, even the older ones.

This is my first experience with a M.2 drive. The drive I am buying is relatively expensive and there is no return policy on it unless it is defective. I wanted consult here and check if M.2 drives are as versatile and compatible as SATA drives?

Is it possible that a laptop has a very specific M.2 specification? This is the case for laptop memory. but I am not sure if M.2 SSDs are universal or not.

Update:

Here is the Lenovo part:

ThinkPad M.2 512GB SATA SSD (4XB0K48501)

Here is the part that I am thinking of buying:

http://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-850-evo-m2-1tb-mz-n5e1t0bw/

Answer 1

I wanted consult here and check if M2 drives are as versatile and compatible as SATA drives?

Yes and no.

First of: There is not a single M.2 option. The M.2 port comes in several flavours, some supporting different standards than others. You want to make sure that you get a M.2 SSD with the same options as your socket provides.

Wikipedia has a nice list of M.2 keys. For a SSD you want a M.2 socket and M.2 device with the M-key. These support both PCIe ×4 and classic SATA.

For the drive you also want the M.2 keyed for M, but that still allows two options:

1. A SSD drive keyed for M with a SATA interface. This has no advantage over a regular SATA SSD drive with the sole exception of a smaller form factor.
2. A SSD drive keyed for M with a PCI-e/NVME interface. This interface can be much faster. Example: the Samsung 960 EVO with read and write speeds up to 3200 MB/s. Way above SATA-III. The NVME protocol is specifically written to SSD and does not make any assumptions about head movements of low queue depts. This is the currently (2016) preferred interface.

So much about background.

Both drives in your post show "SATA M.2". That means they are using the SATA interface over the M.2 connector. They will act as regular SATA drives. The motherboard may disable another SATA port to reroute this tho the M.2 connector. (Many desktop motherboards do, no idea about your laptop). SATA M.2

[Edit] A quick google on your laptop to search which M.2 sockets it had showed me this article.