A (potentially) simple question about m.2 nVME

[Radium_Angel]

I have a system here that does not have built-in m.2 connectors. I did get a simple PCIe adapter and attached my nVME drive to it, and it works fine. There's a performance hit, but I"m okay with this as it's a data/swap drive instead of a boot drive. I'd like to find another adapter that supports multiple m.2 nVME drives, but in looking about I'm not certain if PCIe bifurcation is a required thing, or if the drives will simply be seen as separate drives (I have no need of RAID on them)

 

Mt system is a Dell Precision T5610 and I'm pretty certain it doesn't have Bifurcation supported in the BIOS.

[porina]

There shouldn't be a performance hit, if you compare like with like e.g. CPU lanes or chipset lanes.

 

To my understanding, there needs to be some smarts somewhere as multiple M.2 devices need their own lanes, and a slot by itself isn't going to split it like that. So either needs a card that will do that for you, or support already built in system. I don't think I've seen the latter, not on any system I've had. Bit of a niche use case.

[Firewrath9]

https://www.newegg.com/Product/Product.aspx?Item=2HK-0012-00527

up to 4, if you have the pcie lanes.

[paddy-stone]

2 minutes ago, Firewrath9 said:

https://www.newegg.com/Product/Product.aspx?Item=2HK-0012-00527

up to 4, if you have the pcie lanes.

LOL, was just about to post this  https://www.amazon.co.uk/Asus-Hyper-M-2-X16-Card/dp/B0757XFMJM/ref=sr_1_4?ie=UTF8&qid=1547305217&sr=8-4&keywords=nvme+pcie+adapter

[paddy-stone]

Ahh OP, what board do you have?  as reading through some of the comments, seems like it's limited to x299 for bifurcation AFAIK.

[mariushm]

The card above with 4 m.2 connectors only works if the motherboard's bios supports bifurcation, splitting an x16 into 4 x4  - the card itself doesn't have a chip that would act like a switch to create 4 separate pci-e x4 out of a x16 (like you would do with an expensive 50$+ switch chip)

 

There are Intel motherboards that have two m.2 connectors and both support nvme drives, but they're both connected to the chipset and eventually the data goes to the cpu through the same DMI link that's capped to around 4GB/s

 

On AMD, most AM4 boards have the first m.2 connector connected directly to cpu at pci-e x4 speeds, and the second m.2 may have 1, 2 or 4 lanes coming from chipset - but keep in mind they're pci-e 2.0 lanes, so you get half the speed per lane (so you get at most 2 GB/s).

Bx50 chipsets only have 6 pci-e 2.0 lanes, so some boards prefer to add a pci-e x4 slot and have 2nd m.2 only SATA, some allow you to choose between pci-e slot or m.2 , or allow you to limit to 2 pci-e lanes for m.2 and make the pci-e x4 slot a pci-e x1 one.

xx70 chipsets have 8 pci-e 2.0 lanes, so there's more flexibility.

 

With x370 and x470 AM4 boards, you could install a pci-e x16 adapter board in the second pci-e x16 slot and I think the motherboard would switch the video card to x8 and the second pci-e x16 slot would get 8 lanes, and you could use 4 of those for a second m.2

I'm not 100% it works for any, may require some bios support.

 

On  Threadripper it goes without saying that you can have loads of nvme m.2 connectors as the processor has 60 pci-e lanes available, and most motherboards support bifurcation so besides 2-3 m.2 connectors on board, you can also add such cards like the Asus one above and convert a x16 slot into 4x4 for 4 m.2 drives.

 

[Radium_Angel]

4 hours ago, porina said:

There shouldn't be a performance hit, if you compare like with like e.g. CPU lanes or chipset lanes.

 

To my understanding, there needs to be some smarts somewhere as multiple M.2 devices need their own lanes, and a slot by itself isn't going to split it like that. So either needs a card that will do that for you, or support already built in system. I don't think I've seen the latter, not on any system I've had. Bit of a niche use case.

That's kind of what I figured. I have spare PCIe slots I could use, just thought I'd be able to find one that allows 2 drives in one slot...but perhaps not given this system isn't brand new.

4 hours ago, paddy-stone said:

Ahh OP, what board do you have?

Well, it's a Dell Precision T5610. The board is likely custom for Dell.

Let me see if I can get a CPU-Z screenshot or info for you.

Hang tight....