Does a M.2 PCI-E 2.0 x4 work in a M.2 PCI-E 3.0 x4 slot?

[weust]

As stated in the subject, does a M.2 PCI-E 2.0 x4 work in a M.2 PCI-E 3.0 x4 slot?

I have a Kingston HyperX Predator SSD M.2 + HHHL PCIe adapter 240GB laying around which I don't really use anymore, and was wondering if I could use it in a PCI-E 3.0 x4 M.2 Slot.
Maybe use it as a SLOG with ZFS or perhaps as a boot drive when I build my new desktop once Ryzen 3 comes out. It's fast enough for Windows 10 plus some apps, and beats a SATA SSD anyway.

Normally it's easy. PCI-E is backwards compatible, or at least in general.
But how about M.2 in this equation?

 

[EffrafaxOfWug]

M2 should just be PCIe-over-a-differently-shaped-connector with the device at each end negotiating the highest mutually supported connection, so yes it should work just fine.

 

[tomaash]

Let me phrase it in words of our major infrastructure vendor:
weust.
Yes.

 

[lowfat]

There was no PCIe 2.0 M.2. If the drive you have isn't SATA m.2 then its PCIe 3.0

 

[weust]

@lowfat Check the specs here: https://www.kingston.com/datasheets/shpm2280p2_us.pdf

@EffrafaxOfWug I was thinking that too. Just not sure.

@tomaash Thanks! Who is the vendor?

 

[lowfat]

@lowfat Check the specs here: https://www.kingston.com/datasheets/shpm2280p2_us.pdf

Interesting yet odd. The controller that SSD uses is a PCIe 3.0 controller.

There hasn't been any m.2 slots on a motherboard tied to a PCIe 2.0 controller. PCIe 3.0 was around well before NVMe / m.2 slots were a thing. Either way all PCIe devices are backwards compatible. A PCIe 1.0 device will run in a PCIe 4.0 slot, just as the PCIe 1.0 bandwidth.

 

[EffrafaxOfWug]

There hasn't been any m.2 slots on a motherboard tied to a PCIe 2.0 controller. PCIe 3.0 was around well before NVMe / m.2 slots were a thing.

There are definitely some, depending how your motherboard is put together. For instance the block diagram on some X470 motherboards has a M.2 PCIe 2.0 slot hanging off the chipset rather than the PCIe 3.0 CPU. The X470D4u I'm about to buy apparently has both a 3.0 and 2.0 M.2 slot.