PCIe bifurcation 4x4x4x4 from an x16 slot

[Chaftalie]

Hi!
 

I recently bought an ASUS x16 to 4x m.2 nvme to use my 4 x 1TB intel 660p as NAS storage.

I thought about putting this card into my 24/7 PC (Ryzen 2200G ASRock X370 mini-ITX).

 

EDIT: my "24/7" PC does not have a dedicated graphics card, what it has got is an, 2200G, ASRock X370 mini-ITX, 120GB SSD, some HDDs, 8GB Ram

Its used as an testing server for websites, ftp servers, databases and so on...

 

After some testing I got to the point of realization that that is not as easy as I thought...

At first only one SSD worked after some searching in the BIOS I found an option to split the x16 PCIe into one x4 Slot or into two x8 slots.
That made an second SSD work.

 

After some researching I found out that this techology thats used here is called PCIe bifurcation.
Apparently I was very lucky with my motherboard to get two SSDs working, because in this reddit post  some guys said that only ASRock impliments bifurcation on some of their AM4 Boards (with that one beeing the only one besides its Brother the B350 Version of his board)

 

Is there a very slime chance of getting a 4x4x4x4 bifurcation on this Board (or even another AM4 Board) working?

 

If that is not possible, which consumer platform/Mobos implements PCIe bifurcation for that what I need?

 

 

[GoldenLag]

6 minutes ago, Chaftalie said:

24/7 PC

could you clarify this point?

 

if you mean daily driver means you have a GPU aswell. meaning it is possible, but it will require some trickery. 

 

Ryzen consumer has 20 PCIe lanes where 4 are dedicated to nvme and 16 to the slots. 

 

9 minutes ago, Chaftalie said:

Is there a very slime chance of getting a 4x4x4x4 bifurcation on this Board (or even another AM4 Board) working?

if you use PCIe 16x slot for the m.2 card (in 16x mode) it will allow for the use of all m.2 devices. 

 

https://www.aliexpress.com/item/M-2-NGFF-NVMe-M-Key2280-To-PCIe-3-0-4x-Riser-Card-Cable-PCI-Express/32833359557.html

 

then you will need to use this to get the GPU to run in 4x from the m.2 slot that is directly fed from the CPU. this will mean some performance loss. 

[Chaftalie]

15 minutes ago, GoldenLag said:

could you clarify this point?

I probably have made this part a little unclear. It is an PC thats only used for minior things like as a apache server for testing websites or other similar things, it is running 24/7. It is not used as an user PC. (I will update the main post)

 

21 minutes ago, GoldenLag said:

if you use PCIe 16x slot for the m.2 card (in 16x mode) it will allow for the use of all m.2 devices.  

 

https://www.aliexpress.com/item/M-2-NGFF-NVMe-M-Key2280-To-PCIe-3-0-4x-Riser-Card-Cable-PCI-Express/32833359557.html

 

then you will need to use this to get the GPU to run in 4x from the m.2 slot that is directly fed from the CPU. this will mean some performance loss. 

But how do I do that?
The BIOS I have got at the moment only can do two time 8 lanes as I understand it.

[GoldenLag]

9 minutes ago, Chaftalie said:

But how do I do that?
The BIOS I have got at the moment only can do two time 8 lanes as I understand it.

If you have no other device connected in the slots. It should run the card in 16x mode om the top slot. Though with no videooutput, you cant check this without running a GPU through the m.2 slot. 

 

 

Also i just doublechecked. You have a 2200G which only has 8 lanes dedicated to the slots. In others words, it wont work. 

 

If it is actually running in 8*8 mode. It means the mobo is multiplexing it into 16x 2.0 speed lanes. Which would allow for it to work, but you would need a second m.2 card. 

 

I havent found any multiplex cards sadly. 

[Chaftalie]

19 minutes ago, GoldenLag said:

Also i just doublechecked. You have a 2200G which only has 8 lanes dedicated to the slots. In others words, it wont work. 

Thats a bummer, also the 2400G has only 8 lanes dedicated to the x16 Slot and I do not think there is any CPU for the AM4 sockel with integrated graphics and 16 lanes for the x16 Slot.
 

19 minutes ago, GoldenLag said:

If it is actually running in 8*8 mode. It means the mobo is multiplexing it into 16x 2.0 speed lanes. Which would allow for it to work, but you would need a second m.2 card.

What do you mean wit an second m.2 card?

 

 

If I remember correctly, I heard that Zen3 will support PCIe 4.0. with that it would be possible to run their low end 3200G with 8 x PCIe 4.0 lanes multiplexed to 16x PCIe 3.0 Lanes?

 

 

[Chaftalie]

5 minutes ago, VegetableStu said:

take note that most 4x m.2 adapters (like the one you have in the OP) are passive, so the lane bifurication logic must be done by the motherboard (check BIOS settings in the manual. they will explicitly say a certain x16 slot supports x4/x4/x4/x4 mode if it does). otherwise the board will either not work with the adapter, or just see the first x4 device.

Yep, I learned that the hard way ^^.

5 minutes ago, VegetableStu said:

there are dedicated PCIe multiplexer/bifurcation cards out there, but those are usually aimed at servers and cost server money ._.

I would love getting my hand on one of those ^^

5 minutes ago, VegetableStu said:

also just for reference: mATX and ITX are two different things ._.

Thanks for pointing that out I updated the main post.

[GoldenLag]

11 minutes ago, Chaftalie said:

What do you mean wit an second m.2 card?

The first card will obly allow for 2 devices since it only has 8 lanes. So youd need a second card. 

12 minutes ago, Chaftalie said:

with that it would be possible to run their low end 3200G with 8 x PCIe 4.0 lanes multiplexed to 16x PCIe 3.0 Lanes?

Theoretically, yes. Though we dont know if mobo vendors will accomodate that, and kts somewhat unlikely. And if you want multiplex card you need to cough up server money. At what point a threadripper is cheaper. (you can get mATX threadripper boards)

[racom]

Hi Chaftalie

 

I've got bifurcation working with ASRock X570m Pro4.

https://www.asrock.com/mb/AMD/X570M Pro4/

 

1x16 -> 4x4

 

The setting / support for bifurcation was introduced with BIOS version 2.21 2019/11/25.

The board also supports ECC memory (unbuffered!).

 

I use it now in combination with this card.

https://www.asrock.com/mb/spec/product.asp?Model=ULTRA QUAD M.2 CARD

 

 

Here some pictures.

 

 

 

[weaseal]

racom,

thanks for posting this. I've been struggling to find a microATX mobo that does this 4x4 bifurcation.  Can you tell me, what CPU are you using?

 

Edit: Also can you say, are you able to run discreet GPU at the same time as the Asus Hyper card?  Or are you swapping them for each other to avoid using up all PCIE lanes?

[Chaftalie]

Both X470 AsrockRack Motherboards can use their x16 as 4x4 Bifurcation Slots

Quote

PCIe 3.0 x 16PCIE6: Gen3 x16 link (splittable in x4/4/4/4); auto switch to x8 link when PCIE4 is occupied.PCIE4: Gen3 x8 link

(user manual, second page not counting the index pages user manual | also states that on the page under specifications)

 

X470D4U2-2T (With double 10Gbit Lan)

X470D4U

 

Asrock also has a compatibility list for its quad m2 card, but that list is missing a lot of Asrock Motherboards (already saw X470 and X570 boards working with 4x4).

I was in contact with their support in November and they couldn't give another list with ALL compatible Motherboards 

 

You can run a dedicated GPU from another PCIe Slot (over the Chipset) or use an m2 to PCIe adapter if you really need a GPU with an microATX Board.

 

[Jjziets]

I'm also looking for an adapter to convert x16 to 4 x4(x16 physical) prefeble with a plx pci switch.