Help me understand some stuff about M.2 SSDs

Hey…
So I have build my recent system I love (so far windows behaves). I am fine with my SATA SSD, but I looked around and some questions arose from the depths…

  1. So M.2 SSDs seems to be 2 kinds as far as I understand: PCI-e and SATA. Where does NVMe comes into the picture? How many types of M.2 SSDs are there?
  2. My board have it’s CPU support list, QVL memory support list and Storage support list. My SSD is not in the list, but it works. Does that mean, than any SSD will work, or there are some stuff, that may cause some kinds of issues?
  3. What should I look at, when I look at an M.2 SSD? I mean there is that one Kingston SATA drive for 62 Euro, and then there is the ADATA SX6000 (I love you, ADATA), that is PCIe Gen3x2 for 55 Euro… It is faster, then why it is cheaper?

There are things, I don’t quite understand about M.2 SSDs…

  1. NVMe uses PCIe. For the most part you could consider them interchangeable for the consumer market. SATA is just SATA of course.

  2. Storage tends to work no matter the motherboard if the SSD is built to spec. Some drives might need drivers, but I think most drives are plug and play on the latest operating systems.

  3. I look at speed, capacity, and price. That’s entirely personal preference for what you want/need. I
    bought a Corsair MP500 a while back because I wanted speed followed by capacity at the time for my games, so I spent more money than if I went for a slower drive. More recently I bought a WD Black SSD because I wanted capacity more for a workstation.

    3a. For those two drives specifically it could be a multitude of reasons why the faster drive is cheaper. Sales, clearance, rebates, et cetera.

    3b. The jump from a mechanical drive to a SATA SSD is more noticeable than the jump from a SATA SSD to an NVMe drive, and even less of a difference between low-end and high-end NVMe drives. I guess you could liken it to the law of diminishing returns.

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M.2 = Form factor
SATA(AHCI)/NVMe = Controller Interface

Using a SATA M.2 SSD in a M.2 slot is similar to using a 2.5" SATA and connecting it via cable.
Using a NVMe M.2 SSD in a supported M.2 slot is connecting it directly to the CPU or via PCH(Chipset) typically using 4x PCIe 3.0 lanes.

To help you visualize

The SATA device will be limited by the normal 6Gb/s, whereas the NVMe device will only be limited by the drive itself and available PCIe lanes.

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M.2 SSD’s are pcie, so they should just work. You can use an NVMe drive in any system just like you can use a graphics card in any system, but NVMe drives are only bootable in some boards. This isn’t an issue anymore, but when NVMe drives came out, motherboard bios’s lacked what was basically a driver that instructed a motherboard on how to boot from NVMe. Now that motherboards all have this piece of software in their bios’s, its plug and play across the board with new systems and NVMe drives.

Kingston are expensive because of their name, not because of their quality anymore imo. When you look at M.2 ssd’s, the first thing is to look at the “key” of a drive.

  • M-Key = PCIE
  • B+M-Key = SATA

Once you make sure your motherboard can support either B+M or M key drives depending on what you’re looking for, then its really just comparing speeds and capacity. Except for Samsung drives, you can expect all PCIE M.2’s to overheat if you do long, sustained reads/writes. It varies depending on the drive controller and NAND type / manufacture how fast the drive will be, but its really just comparing spec sheets to see which is faster.

In general, Samsung M.2’s are the best and everything else is just a hierarchy of what has the better paper numbers. The hype is actually deserved with Samsung’s 960 series though, as the 960 series are the only PCIE M.2 drives that don’t thermal throttle under sustained-load without a heatsink.


To compare the two drives your looking at, I’m going to assume you’re looking at the base versions of the SX6000 and Kingston Blue M.2 version.

The SX6000 is slightly faster but not exactly a showcase of NMVe potential, while the Blue M.2 is really just a budget Sata drive in M.2 clothes. Neither the SX6000 or Blue are going to win speed competitions, but the SX6000 has slightly higher R/W figures. Idk if you’ll really feel the ~200Mbps added read and writes of the SX6000, so IMO I’d just go for whichever has more capacity.

Really NVMe shines when you get IOPS performance beyond what sata can offer, but the SX6000’s controller can only muster Sata levels of IOP performance, so its kinda whatever. On a positive note on the SX6000, it not being one of the multiple of thousands of MBps NVMe drives means it may actually not thermal throttle like its bigger brothers :grin:

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Are you confused yet?

M.2 is a type of connector that can support a sata connection back to a sata controller or a direct pcie connection that uses nvme protocol.

The m.2 connector can be configured to support either sata nvme or both. The ssd sticks are configured either as sata or nvme.

Sata is limited to a read write speed of about 500MB/s. Nvme read write speeds are up to 2000-3000MB/s

As has been mentioned already, you need to pay attention to what the m.2 slot u want to use supports and then choose the appropriate type of m.2 stick

Kingston SM2280S3G2 and ASX6000NP-128GT-C. Both of them 128GB. The ADATA is the same price as a 2,5" SSD…

I don’t really need any of it. I have a cheap ADATA SP900 drive from 4 years ago, but it’s only 64GB. I still have 25 of them free, but …

Actually this is clearing stuff in my mind… The keys are confusing me now…

I have a PCI-E M.2 slot directly to the CPU and a SATA M.2 slot through the chipset, sharing bandwidth with my SATA connections. So depending on what I get, I will plug it in the proper slot.

OK, thank you, everyone and have a nice holidays :slight_smile:
I am still confused about the keys though… Why those even exist?

M.2 supports a lot of data interfaces. The keys are there so people don’t plug the wrong type of device into the wrong slot.

From Wikipedia:

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unless you are space constrained, M.2 Sata is really a waste of money.

standard sata 2.5" ssd perfrom the same and are cheaper than the m.2 versions.

An NVMe drive connected to the slot that is directly connected to the CPU is the best performance option. Do not bother with the Intel 600p drive. it is at the budget end of the NVMe drives but it really doesnt perform any better than a sata drive

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this may help

I know its petty, but M.2 is the connector, not a form factor. The part that says 2280 or 2260 after the M.2 designation is the form factor.

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If we’re gonna be pedantic, then M.2 SSD used to be called NGFF(Next Generation Form Factor), but later got changed to M.2, which is used to name both the SSD and the connector, so M.2 is indeed a form factor.
But don’t take my word for it, allow me to quote PCI-SIG directly from the M.2 Rev 1.0 specification announcement.

As a natural progression from PCIe® Mini Card and PCIe® Half Mini Card, the smaller M.2
form factor is designed to meet future market requirements for applications in thin mobile
platforms, such as tablets, portable gaming devices, smartphones and devices requiring
SSDs.

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image

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What do you expect when you ask a forum full of OCD nerds?

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Ignore all the distracting ramblings posted before.

At it’s basis M.2 is a specification. It specifies both physical connector design and electrical signaling characteristics for a PCI-e connector to suit low profile(for use in embedded/small devices) encompassing many form factors as long as they comply with the M.2 specification.

What is M.2? Is it the same as NGFF?

M.2 was developed by the PCI-SIG and SATA-IO standards organizations and is defined in the PCI-SIG M.2 and the SATA Rev. 3.2 specifications. It was originally called the Next Generation Form Factor (NGFF), and then formally renamed to M.2 in 2013. Many people still refer to M.2 as NGFF.

The M.2 small form factor applies to many add-in card types, such as Wi-Fi, Bluetooth, satellite navigation, Near Field Communication (NFC), digital radio, Wireless Gigabit Alliance (WiGig), Wireless WAN (WWAN), and Solid-State Drives (SSDs).

M.2 has a subset of specific form factors strictly for SSDs.

In short the Kingston M.2 FAQ will answer all your questions.

Initially it started as a further development to broaden the capabilities of M-PCIe and PCIe_MiniCard and mSata as previously used for WiFi/Flash cards in mobile/embedded devices as well as to increase it’s IO in line with newer PCI-e capabilities.

M.2 together with PCI-e thus provides a bridge for a variety of devices to communicate via various protocols.

One such protocol/interface is NVMe

NVM Express which is a register level interface that allows host software to communicate with a nonvolatile memory subsystem, typically over PCI-e.

I would love to link you the PDF I have for M.2 spec directly, but unfortunately it’s restricted to PCI_SIG members only (silly I know).

http://pcisig.com/specifications/pciexpress/M.2_Specification/

If you’re a creative researcher I’m sure you can obtain it if you’re interested enough.

It’s nothing special or particularly ground breaking to start a flame war over.

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