PCIE Bifurcation

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
Either asrock x299e-itx or x99e-itx.
Or the server counterparts from asrock.

I don't have any of the behind itx in stock currently.

Let me know!
 
Joined
Nov 20, 2017
Messages
59
That's so disappointing that I'd have to step all the way up to that board.... With people demoing a 4x m.2 card for Ryzen 3000 maybe we'll get x4x4x4x4 support on x570. Because I'm really pondering a PfSense router with 10G ethernet cards.... And your riser board looks perfect if someone would just support it on a reasonably priced platform. I'll potentially order one in a few months... IF x570 supports it. I love your work though! As a case scratch builder I'm seriously looking at your risers and pondering builds.
 

haestrod

n00b
Joined
Jun 20, 2019
Messages
1
Has anyone been successful in modding a BIOS to engage in bifurcation? Specifically an Asus Strix X470-I? Although I would be interested to hear success stories with any board.

Edit: I'm aware of www. win-raid. com/t3323f16-Guide-How-to-Bifurcate-a-PCI-E-slot.html
 
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Joined
Nov 20, 2017
Messages
59
Update on my PLX work:

It does work with some Lanes missing (maybe bad BGA solder joints?)
Assembling took me a whole day though.
Lets see if I can make these available sooner or later.
How does this work? Does the bios have to support the PLX application? I'm familiar with the theory of PLX, but how does this turn out in practice when it's not implemented directly on the motherboard?
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
BIOS support is not necessary AFAIK. Otherwise dual GPU cards wouldn't work either. It works fine with my X99E and it should work with any mainboard.

The issue I currently have is that I haven't figured out a reasonable way to manufacture these in little quantities.
Hand assembly is NOT an option, took me a complete day.

I will keep you posted.
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
Unfortunately I had no time yet to work on the dan-project. Also I will be on a vacation for the next 3 weeks, so it will have to wait a bit longer. But I won't forget about it!
 

extide

2[H]4U
Joined
Dec 19, 2008
Messages
3,494
I'm fairly sure the MSI Creation supports it at least -- it comes with a M.2 adapter to put 2x M.2's in a PCIe 8x slot -- no PLX chip. I actually have the board but no cpu/ram yet but I will be getting the rest of my parts in over the next few weeks.
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
OK: First results with ryzen 3000 and PCIe gen4:

Summary:
The Gigabyte X570 I Aorus Pro WIFI Mini-ITX supports bifurcation even with its stock BIOS, all modes (x8x8, x8x4x4 and x4x4x4x4 are available... YAY!!!!!)
I have Sucessfully tested x8x8 and x8x4x4 with 4 different versions of my existing risers.

Using one of my risers with the card in the topmost slot(longest traces) did not impact performance (pic 1+2)
gen4 x8 yields around 13500 MByte/sec and there is no difference between card in Slot and card in Riser. (Raw should be 16000, but one has to deduct overhead!)
I also tested an 50cm LinkUp Riser cable which works without speed-drops as well.

What did NOT work was plugging my Riser into the LinkUp cable. Speed dropped to gen1. (Although I could probably set it to gen3 via BIOS, had it set to Auto here)

I have ordered A Dan-Cases A4-SFX and will report how the Flex-Riser in that case will work together with my Risers.

Also I enquired DIODES inc. for a datasheet for their gen4 redrivers (the ones that are used on pretty much every 3 Slot ATX board for the second slot)
Sadly no reply yet. Those Chips are available on digikey though... Maybe i will go through the hoops and reverse engineer the Pinout...

Anyways I would conclude this to be good news.
Bifurcated gen4 builds are in fact possible with my risers as they are right now. (For example with the GPU placed directly next or above the mainboard without using any additional cabling)
Further testing will be neccessary and follow as soon as I get the time and hardware.

IMAG2994.jpg
IMAG2995.jpg
IMAG2996.jpg
 

DaHans

n00b
Joined
May 21, 2015
Messages
38
Wow, thanks for testing. Sounds great that Bifurcation is suported out of the box.

DAN also mentioned, that PCIe4.0 doesnt work with the risers in Dan CAse v3 and 4. Link

So maybe some peaople have to order a new riser for getting PCIe 4.0.

Looking forward for the Bifurcation solution in the DAN A4 with you risers. :)
 
Joined
Nov 20, 2017
Messages
59
Btw those looking for a mini-tower case that supports bifurcation with very little work, I do recommend the Neo-G (http://metallicgear.com/products/Neo-G-Series-mITX). It's not the smallest case, but it's pretty, does a decent job supporting AIOs/watercooling, and is super easy to support a bifurcation riser. To use a bifurcation riser just get some motherboard standoffs, some washers, and drill 4 holes. I can post pictures of my set up Thursday probably, I'm planning to build my own case eventually but wanted a case for my new 3900x so I can use it in the meantime.
 

Meepcmx

n00b
Joined
Aug 20, 2019
Messages
3
Does anone have any insights into how these risers behave with IOMMU groups? Will any devices attached to the split ports end up in the same group, or will/can they be in seperate groups (for device passthrough to virtual machines)
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
On my x99 with x8x8 the GPUs ended up in separate IOMMU groups.
I suppose this would be the standard behavior.
 

Meepcmx

n00b
Joined
Aug 20, 2019
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3
On my x99 with x8x8 the GPUs ended up in separate IOMMU groups.
I suppose this would be the standard behavior.
Thanks for that insight. I have a slightly different use case than discussed here in that I’m interested in maximizing pcie slot availability for virtualization and device pass through (usb adapters and the like).

I had a look at your site and will likely be placing an order. Wondering, however, if there’s a version of the 4x4x4x4 breakout card with a lower slot pitch. They are set up for dual slot cards, but I’d be needing only single slot, so could tolerate the slots being closer together, and therefore taking up less space overall.
 
Joined
Nov 20, 2017
Messages
59
C_Payne I would love to design some cases for your amazing risers, sadly I only have experience making acrylic cases (similar to Parvum). I wonder if you've explored reaching out to some of the SFF case companies such as Sliger to see if they would be interested in working with you for bifurcation cases?
 

fireworm

n00b
Joined
Sep 2, 2019
Messages
3
Hey guys, wondering if anyone could help me troubleshoot / debug my pci bifurcation setup:

MOBO: Gigabyte z270 WIFI Itx
CPU: i7-7700k
GPU: EVGA 1080 ti FTW3

Splitter: ARC1-PERY423-C20
Other PCI card: Intel 10gbit card

When I plug it all up and boot into Windows, I can successfully see my 10gb pci card.

Using the onboard graphics, I cannot see my 1080ti in device maanger (it is connected to another monitor). I can't install nvidia drivers either (at least the one's I downloaded from the nvidia site, 435.xx).

I looked in hwinfo, and saw the 'gp(102)' (which is the code name for the 1080ti), but couldn't see it in device manager, and couldn't manually install the driver either.

I rebooted, and now I don't see the 1080ti in hwinfo anymore. Card does light up and spin fans on boot.

Any ideas would be much appreciated.
 

cyklondx

Limp Gawd
Joined
Mar 19, 2018
Messages
419
Hey guys, wondering if anyone could help me troubleshoot / debug my pci bifurcation setup:

MOBO: Gigabyte z270 WIFI Itx
CPU: i7-7700k
GPU: EVGA 1080 ti FTW3

Splitter: ARC1-PERY423-C20
Other PCI card: Intel 10gbit card

When I plug it all up and boot into Windows, I can successfully see my 10gb pci card.

Using the onboard graphics, I cannot see my 1080ti in device maanger (it is connected to another monitor). I can't install nvidia drivers either (at least the one's I downloaded from the nvidia site, 435.xx).

I looked in hwinfo, and saw the 'gp(102)' (which is the code name for the 1080ti), but couldn't see it in device manager, and couldn't manually install the driver either.

I rebooted, and now I don't see the 1080ti in hwinfo anymore. Card does light up and spin fans on boot.

Any ideas would be much appreciated.
that mobo does not support bifurcation. Only couple z270 mobo's supported it (mining mobo's with bios option for it).
 

fireworm

n00b
Joined
Sep 2, 2019
Messages
3
that mobo does not support bifurcation. Only couple z270 mobo's supported it (mining mobo's with bios option for it).
It was in their marketed features so I'd be inclined to say it should work.
BIOS for this MOBO does indeed have the 2x8 PCI Split option. Anyway, I disassembled everything and laid it out on my desk trying different combos, (found I did have one bad riser, GPU wouldn't boot when it was connected through this riser to my MOBO, with no splitter).

After trying some some combos and risers and no risers and a different computer (to verify the GPU even still worked):

The splitter didn't like the gpu when I had a riser between them.

So, this setup did NOT work: mobo > 20cm riser > Splitter > 5cm riser > GPU.
But this setup DID work: mobo > 20cm riser > Splitter > GPU.

This is kind of annoying because I can't put my GPU into the bottom slot of the splitter, and use another riser out of the top slot (because the splitter is now trying to go into my Dan Case / mobo). So, I'll have to put the gpu in the 'top' slot, and a riser between the GPU and splitter in the bottom slot. I tried this, and it doesn't fit vertically due to the GPU's heatsink being very close to the slot, so I'm gonna file down another riser for the 10gb nic and make it sit deeper into the splitter, and hope that works.
 

fireworm

n00b
Joined
Sep 2, 2019
Messages
3
BIOS for this MOBO does indeed have the 2x8 PCI Split option. Anyway, I disassembled everything and laid it out on my desk trying different combos, (found I did have one bad riser, GPU wouldn't boot when it was connected through this riser to my MOBO, with no splitter).

After trying some some combos and risers and no risers and a different computer (to verify the GPU even still worked):

The splitter didn't like the gpu when I had a riser between them.

So, this setup did NOT work: mobo > 20cm riser > Splitter > 5cm riser > GPU.
But this setup DID work: mobo > 20cm riser > Splitter > GPU.

This is kind of annoying because I can't put my GPU into the bottom slot of the splitter, and use another riser out of the top slot (because the splitter is now trying to go into my Dan Case / mobo). So, I'll have to put the gpu in the 'top' slot, and a riser between the GPU and splitter in the bottom slot. I tried this, and it doesn't fit vertically due to the GPU's heatsink being very close to the slot, so I'm gonna file down another riser for the 10gb nic and make it sit deeper into the splitter, and hope that works.
Some more experimenting showed the following result:

MOBO > Splitter > [20cm Riser > GPU] + [20cm Riser > 10gb card] = Works fine, slot doesn't matter.

Looks like the real issue was doing MOBO > Another Riser > Splitter.

This means you need a splitter which has a long riser [MOBO > Splitter's Riser > Splitter's PCB], if you hope to move the Splitter PCB out of the CPU chamber.

My Splitter has a small 5cm riser on itself (it's not just a pluggable pcb), so I'm SOL for keeping my CPU chamber breathable. :(

Hope that's not confusing, and hope it helps someone else out there.
 

AP2

[H]ard|Gawd
Joined
Jun 25, 2007
Messages
1,484
Just curious would bifurcation plus NVLink affect performance of 2 2080tis on mini itx setup?
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
It will be just the same compared to a mainstream CPU (16 Lanes total) on an ATX board. Nothing different happening.
 

ChronoDog

Weaksauce
Joined
Oct 15, 2009
Messages
111
Does anyone know of a bifurcated (x8x8) riser that's both rigid and flexible?
Basically, the idea would be to use a 905P (or any other HHHL card) along with a 2-slot GPU in an NCase M1.
The SSD would sit over the PCIe slot, with the graphics card one slot below it.

What I'm getting at, is something like this:

uOgreZW.jpg


With the top part of this (but in x8) attached to the left side of it it:

3flJXt0.jpg


I looked around, but can't seem to find anything like that.
 
Joined
Nov 20, 2017
Messages
59
Does anyone know of a bifurcated (x8x8) riser that's both rigid and flexible?
Basically, the idea would be to use a 905P (or any other HHHL card) along with a 2-slot GPU in an NCase M1.
The SSD would sit over the PCIe slot, with the graphics card one slot below it.

What I'm getting at, is something like this:

View attachment 189718

With the top part of this (but in x8) attached to the left side of it it:

View attachment 189719

I looked around, but can't seem to find anything like that.
Like this? http://www.ameri-rack.com/ARC2-PELY423-C7_m.html
If you do want it you have to call/email them and they'll get you an invoice to pay and then ship it out to you, those risers are excellent, I have several.
 

ChronoDog

Weaksauce
Joined
Oct 15, 2009
Messages
111
Like this? http://www.ameri-rack.com/ARC2-PELY423-C7_m.html
If you do want it you have to call/email them and they'll get you an invoice to pay and then ship it out to you, those risers are excellent, I have several.
I already have exactly that in an A4-SFX, see here, but that's not what I mean and doesn't fit the purpose, unfortunately.
What I'm loking for is a rigid riser that will basically turn a half-height (low-profile) single-slot PCIe card into a full-height one, whilst also adding another PCIe x16 (x8 electrically) slot right next to the existing one using a flexible cable.

Here's a limpy Paint representation, which hopefully explains it better:

unUuZLn.png
 
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ChronoDog

Weaksauce
Joined
Oct 15, 2009
Messages
111
Just so you know low profile cards have a bracket that turns the opposite way from a full slot bracket. Which is probably why that doesn't exist (as far as I know)

Edit: Cool idea though, that would be awesome if that existed!
Upward risers do exist, just not bifurcated ones.
The goal is bifurcating a PCIe slot while keeping a low-profile expansion card in the same place without using multiple risers.
 

C_Payne

Limp Gawd
Joined
Jan 6, 2017
Messages
138
I have actually just recently made a low profile to full height riser and also made a long time ago a bifurcated one for an M.2 slot. (search this thread)
Spacing is very tight though and I don't have the tools to work with small twinax cables. (yet) Maybe I can figure something out with an angled slot...
 
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