Alienware 15 R2 M.2 SSD

2 PCIe M.2 slots. Some SATA SSDs (with the B+M key) will also work.

It was my understanding that a SATA M.2 SSD would not work in a PCIe M.2 slot. Are the two compatible?

"It is important to reference the product manual to determine if the host system supports M.2 SATA or M.2 PCIe SSDs. A SATA M.2 SSD will not function in a PCIe M.2 socket, and vice versa. Both PCIe and SATA have presence detection, which ensures that if the user inserts the wrong SSD into the socket it will not destroy the unit."

http://www.tomsitpro.com/articles/datacenter-m.2-ssd-pcie-specification,2-950.html

Doesnt look like it, which is why I was wondering which type the Alienware 15 has.

The configuration utility on the Alienware site makes mention of being able to have a SATA or PCIe SSD.

Some won't because of a physical incompatibility. However, some SATA M.2s will fit inside a PCIe M.2 slot.

Alienware does use both SATA and PCIe SSDs in their laptops, so I would assume they are using a B & M keyed M.2.

I know a B-keyed M.2 won't work in a M.key slot and vice versa, but a B & M keyed M.2 should work in both slots fine.

"There are four keys, but SSDs only use the B Key and the M Key. The graphic above illustrates the three key configurations present on M.2 SSD connectors. The B Key and M Key will only slide into their respective sockets. SATA M.2 and PCIe 2.0 x2 SSDs work in B and M sockets, so the B & M Key connector enables their use in both types of sockets. It is important to note that the M Key is the only means to receive a PCIe x4 connection." - from your source

I understand they key types but theres also the different interface type. Just because it will fit doesnt mean it will work. According to the linked article SATA and PCIe are not compatible.

Since Alienware sells both SATA and PCIe SSDs in the same laptop I was trying to make sure I know which ports are there and how many of each.

Ahh missed that bit. So they've combined them, very nice.. Thanks for the help!

i have 17 r3, which has identical mobo with 15 r2. my current boot os drive is a samsung evo 850 500gb sata3.

So I just bought the m.2 version of the Samsung 850 EVO (500g) from amazon and am planning on cloning the stock 128g to it and using the new drive as my main boot drive.

In step by step order- can someone confirm I'm on the right track?

-Clone old SSD to new 850 EVO

-Insert new 850 EVO, boot and test for stability

-Reinsert old SSD into new slot, wipe the drive

-Can I now combine them into a new C: drive?  I know the Motherboard doesnt support RAID- just want to know what to expect since it seems a lot of people have done this.

Sounds about right, I went for a fresh load of Windows when I did it though so cant comment much on cloning.

Also, fairly certain you can create RAID arrays.. at least on my 15 R2. What laptop do you have?

If you set the SATA controller to RAID in the BIOS, you can create the array right there.

How did the 850 EVO work out for you? I was thinking about getting a Samsung PCIe NVME drive, but I've decided to go for a lower cost SATA option instead, since they're half the price for the same capacity.

It worked out fine- the cloning was very simple using Samsung's provided technology.  I'm still experiencing occasional slow load times, but much less frequently than before and data within the EVO is fantastic.