PCIE Bifurcation

XGX13XGX

n00b
Joined
Apr 7, 2021
Messages
2
NEED HELP ASAP LOL; So i am a GPU Miner and need some help. the new 3060 gpus req at least x8 lanes, i hace a Dell T5610 server with dual xeon processors, the processors can run 80 lanes, the mother board has 4 x16 PCIe slots. What i want to do is take a x16 to x16 ribbon cable attach a x16 to 2 x8 riser then use 2 x8 to x16 to connect the gpus to the riser card enabling me to have 8 of the 3060s running on the x16 slots and then run 4 more NON 3060 cards off a x1 to x4 riser card. problem is i can not find a riser capable of doing such. I went online and found what i thought would work but it turns out it was a U2 TO 2 X8 NOT A X16 TO 2 X8 any one have an idea how i can attach a U2 to a x16 slot on the motherboard OR where i can find a x16 to dual x8 slot riser card? ive been looking and looking and cant find anything available
 
Joined
May 21, 2012
Messages
2
OK.. got my low profile x8 -> x4 + M.2 Riser ready and tested.
PCIe working as expected.. polarity inversion on clock and data as well as lane reversal.
Also my M.2 socket footprint seems to be working perfectly.

Only thing I didnt get right is the height, so one cannot directly use the low profile bracket to screw into the full height slot as intended.
(I took the specified card height for low profile cards and not the slot height for my calculations which is obviously stupid:banghead:)

Take a look. As always I have spare PCB's to sell should anyone be interested.


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Are these risers available? (with correct height :))
I've got a x4 10Gbps NIC (it's a half-height card) in the second PCI-E x16 slot, and I want to add another NVME SSD to my system, and would like it to have full bandwidth.
It's a X470 K4 Gaming board with x8x4x4 and x4x4x4x4 bifurcation options in the BIOS.
 
Last edited:

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
155
Hi Guys! sorry for being unresponsive here. That always happens to me because the forum just sends one eMail for the first new post and I tend to miss it.

I have moved my store to a new location: c-payne.com

The Coolest: PCIe Bifurcation Card - x8x4xM.2 - low Profile Adapter - Ncase M1 and others
XGX13XGX: PCIe Bifurcation Card - x8x8 - 3W
inf3rno:
https://www.ruten.com.tw/item/show?22030929704581 : These are known to be non functional (check like 10-15 pages back, not sure exactly where)
https://www.asrockind.com/en-gb/PCIE-Riser-2S : This one can only work in some specific mainboards that have 2 clock outputs. Its not suitable for the normal standard PCIe Slot Pinout.
The IOI brand is decent.

3. If the motherboard has two x16 slots and supports for example x16 for the first and x8 for the second, then can I do 2x8 bifurcation for the first slot and use 3 cards with x8 connectors? Or should the motherboard manual explicitly write if this is possible?:
That will NOT work on the mainstream platforms (Ryzen, Intel Mainstream) The CPU only has 16 Lanes. So if you insert a card in the second slot, the first slot will go into x8 mode.
Its a different story on threadripper/EPYC or intel hedt/XEON

5. Is using PCIE x16 -> 4x M2 -> PCIE 4x4 a legit way to split up an x16 port or better to use x16 -> 4x4 bifurcation risers? Is it possible to split up and x16 slot with a PCIE -> M2 adapter even if the motherboard does not support bifurcation for that slot?
There is PCIe-> M.2 adapters with a Packet switch on board, but thats not the Asus one, thats just plain bifurcation and would not work if your mainboard does not support bifurcation.
They cheapest ones are around 150 bucks on aliExpress featuring an ASM2824 chip.
If going the bifurcation way: every added interconnect will add signal loss and you may end up with degraded perfowmance or a lot of AER reports/crashes.

One note about the riser.maxcloudon.com cards: Their claim to be gen4 is to be taken with a large spoon of salt. It is most likely not the case.
 

XGX13XGX

n00b
Joined
Apr 7, 2021
Messages
2
Hi Guys! sorry for being unresponsive here. That always happens to me because the forum just sends one eMail for the first new post and I tend to miss it.

I have moved my store to a new location: c-payne.com

The Coolest: PCIe Bifurcation Card - x8x4xM.2 - low Profile Adapter - Ncase M1 and others
XGX13XGX: PCIe Bifurcation Card - x8x8 - 3W
inf3rno:
https://www.ruten.com.tw/item/show?22030929704581 : These are known to be non functional (check like 10-15 pages back, not sure exactly where)
https://www.asrockind.com/en-gb/PCIE-Riser-2S : This one can only work in some specific mainboards that have 2 clock outputs. Its not suitable for the normal standard PCIe Slot Pinout.
The IOI brand is decent.

3. If the motherboard has two x16 slots and supports for example x16 for the first and x8 for the second, then can I do 2x8 bifurcation for the first slot and use 3 cards with x8 connectors? Or should the motherboard manual explicitly write if this is possible?:
That will NOT work on the mainstream platforms (Ryzen, Intel Mainstream) The CPU only has 16 Lanes. So if you insert a card in the second slot, the first slot will go into x8 mode.
Its a different story on threadripper/EPYC or intel hedt/XEON

5. Is using PCIE x16 -> 4x M2 -> PCIE 4x4 a legit way to split up an x16 port or better to use x16 -> 4x4 bifurcation risers? Is it possible to split up and x16 slot with a PCIE -> M2 adapter even if the motherboard does not support bifurcation for that slot?
There is PCIe-> M.2 adapters with a Packet switch on board, but thats not the Asus one, thats just plain bifurcation and would not work if your mainboard does not support bifurcation.
They cheapest ones are around 150 bucks on aliExpress featuring an ASM2824 chip.
If going the bifurcation way: every added interconnect will add signal loss and you may end up with degraded perfowmance or a lot of AER reports/crashes.

One note about the riser.maxcloudon.com cards: Their claim to be gen4 is to be taken with a large spoon of salt. It is most likely not the case.
i think we were speaking on ebay about the boards, and we came to the conclusion that these would not work cause the server i am using does not support bifrucation. but with that what about the plx switch chips? essentially i am gpu mining and the new cards have mining limiters on them and they REQUIRE X8 OR X16 and when using a x8 you have to have a x8 to x16 adapter to run them. the motherboard i am using can run 80 lanes with the 2 cpus, it has 4 x16 slots and 1 x16 slot wired as a x4 what i need is a splitter with a plx chip the can split the x16 in 2 or 3 but still run at either x8 or 16
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
155
with a Packet switch (PLX) you can use any uplink, even x1. The mining limiter wont interfere as long as the Downstream GPU Link is x8.

I have some PLX boards in manufacturing currently.
 
Joined
May 21, 2012
Messages
2
C_Payne, I'm interested in a x8 -> x4x4 card.
I have a GPU in the first x16 slot, and want to have both my 10G NIC (x4) and another NVME SSD in the second x16 slot.
I'm just wondering, if such a card is available, and how much it would be.
 
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