PCIE Bifurcation

chemist_slime

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No progress on USB 3.0 yet–– I think all of these issues will go away when Apple refreshes the Mac Pro and OS X gets official C612 support.

That's interesting about the Geekbench score. In addition to speedstep, you can get turbo working by adding -xcpm as a bootflag and 0x0306A0 as a fakeCPUID in your config.plist with USB 3.0 disabled. Should boost both single and multi-thread results!

Yea, I did that as well, geekbench score above also have that config.
 

jb1

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Yea, I did that as well, geekbench score above also have that config.

Alright, I'm not sure what robinqu did to get such a great score. I'm running a 2690 which should yield even better performance than the 2676. While I get better single threaded performance, my multi-threaded is around what you've reported.

Just curious, what are the max turbo's allowed for the 2676? I've seen 3.0 GHz mentioned online, but I assume that's single threaded. What is the max turbo for all cores? If you're feeling brave you could see if you can increase the max all core turbo to 3.0 GHz in the BIOS. I'm able to increase the all core turbo to match the single threaded turbo, but the BIOS won't allow me to exceed it.
 

chemist_slime

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Alright, I'm not sure what robinqu did to get such a great score. I'm running a 2690 which should yield even better performance than the 2676. While I get better single threaded performance, my multi-threaded is around what you've reported.

Just curious, what are the max turbo's allowed for the 2676? I've seen 3.0 GHz mentioned online, but I assume that's single threaded. What is the max turbo for all cores? If you're feeling brave you could see if you can increase the max all core turbo to 3.0 GHz in the BIOS. I'm able to increase the all core turbo to match the single threaded turbo, but the BIOS won't allow me to exceed it.

I'll give that a try tonight and see if it held. Did you replace your 2676 with a 2690 for any particular reason?
 

jb1

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I'll give that a try tonight and see if it held. Did you replace your 2676 with a 2690 for any particular reason?

Ah no, I actually ended up getting the 2690 instead of the 2676 because I found a good value for it. They should preform similarly, I think the largest difference is probably that the 2676 tops out at 3.0 GHz (I think) whereas the 2690 tops out at 3.5 GHz for 1-2 core clocks.
 

jb1

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@chemist_slime,
Any update on your build? Really interested to see how you plan to position the two GPUs relative to your board! Still waiting for EK post this connector to the webstore.
 

boloisbolo

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Longtime lurker of hardforum and saw this thread. You guys rock! I would love to get in on this action.
 

chemist_slime

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@chemist_slime,
Any update on your build? Really interested to see how you plan to position the two GPUs relative to your board! Still waiting for EK post this connector to the webstore.

Still working on it! I should have something to show soon. :)
 

jb1

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Still working on it! I should have something to show soon. :)

Looking forward to seeing it! What type of radiators are you using for your design? I'm also trying to figure this out for my own bifurcation build. My current thought is a thin 120mm rad for the two GPUs in Dondan's eventual case, or a 240mm rad for CPU+GPUs in the M1.
 

spoki0

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In lack of Mini-DTX motherboards, this would solve my craving for a tiny double GPU gaming case.

Now I just need to make the case...
And buy the components...



Looking forward to seeing it! What type of radiators are you using for your design? I'm also trying to figure this out for my own bifurcation build. My current thought is a thin 120mm rad for the two GPUs in Dondan's eventual case, or a 240mm rad for CPU+GPUs in the M1.

A tad off topic of this thread, but isn't it generally recommended to have at least one 120x120mm radiator for each component?
 

alfaSZ

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Hi guys, long time lurker here too. Asrock just provided me with firmware 1.50a which basically enables PCIe bifurcation (together with 16GB UDIMM support) so I was able to play around testing the amerirack v3 splitter chemist_slime has been talking about earlier in the thread. Only spent a short time tonight but tried the 8x8x mode with one of GTX650 or GTX970 I had lying around. So only one card at a time both with and without the splitter. The machine boots up into Win10 and runs for a bit but USB devices work erratically (had to unplug/replug mouse a couple of times for it to work) and after a few minutes the whole machine freezes. Didn't try two card simultaneously as I would have to perform serious surgery on them and I am not at that stage yet ;-) Is this similar to your experience? Been using completely stock settings in the UEFI other than the 8x8x. Didn't even try booting the El Capitan partition yet, figured that would be even more of a long shot.. Any input appreciated, will post more experiences when I get more time to play around..
 

boloisbolo

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z97 asrock with bios and ameri rack splitter seems to be working. WOo
 

nekrosoft13

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really cool stuff. I have a board that supports Bifurcation, what would you guys recomend as a best riser to split 8x pcie to two?
 

rozjan

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Maybe here someone could help me. I've an ASRock x99e itx/ac which I'm using with a pci express riser provided with the case a Deepcool Tristellar.

Now I get a lot of:

''Whea logger Event 17: A corrected hardware error has occurred''

Component: PCI Express Root Port

Error Source: Advanced Error Reporting (PCI Express)

Bus Device:Function: 0x0:0x3:0x0

Vendor ID Device ID: 0x8086:0x340a

Class Code: 0x30400


Here what I've discovered:

1) The video card (a gigabyte gtx 970 G1 gaming) works well on another pc;

2) The video card works well when hosted directly into the motherboard;

3) The pci express riser cable show no issue when installed on another motherbord with the same video card.

So I tried the beta bios (1.20E) for bifurcation/riser but got the same issue.

I've also replaced the motherboard and the riser with the same results.

Do your riser show the same error, what could be the origin of the issue?
 
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einmannbude

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Just received a (working, finally) ASrock Z170 Gaming ITX. There is what appears to be an option for PCIe bifurcation in the out-of-the-box (1.0) BIOS.

I have looked through the manual of the mainboard online, because I don't own one yet but intent to buy one in the future. I didn't find an entry for "Riser Card Support" or "PCIE1 Link Speed" in the manual. Just to be sure: This is the Fatal1ty Z170 Gaming-ITX/ac, right? And I guess the feature just didn't make it into the manual.
 

einmannbude

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I have looked through the manual of the mainboard online, because I don't own one yet but intent to buy one in the future. I didn't find an entry for "Riser Card Support" or "PCIE1 Link Speed" in the manual. Just to be sure: This is the Fatal1ty Z170 Gaming-ITX/ac, right? And I guess the feature just didn't make it into the manual.

OK, I looked at the Z170M-ITX/ac manual and there is "Riser Card Support" in. Never mind.
 

jb1

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Well I have an update! I have a custom case for my bifurcated setup.

Very cool! What did the final volume come to for this design? It looks like it supports a 240mm rad and a 120mm rad, is that correct?
 

shadyguido

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Is there any reason why you wouldn't be able to use a 150mm PCIe extension cable in addition to the bifurcation riser?
 

iFreilicht

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Is there any reason why you wouldn't be able to use a 150mm PCIe extension cable in addition to the bifurcation riser?

Maybe you'd get a bit of a performance loss and if you're unlucky an unstable setup, but if it's high quality and well-shielded, there shouldn't be a problem with that sort of setup.
 

MarcWolfe

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For all of you with the Asrock X99E-ITX/ac motherboard. Have you tried an M.2 to PCIe adapter (like in this picture) with a PCIe riser for the second card? The Asrock X99 M.2 slot is PCIe gen 3 4x, thats plenty for a graphics card.

 
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iFreilicht

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For all of you with the Asrock X99E-ITX/ac motherboard. Have you tried an M.2 to PCIe adapter (like in this picture) with a PCIe riser for the second card? The Asrock X99 M.2 slot is PCIe gen 3 4x, thats plenty for a graphics card.


The problem with that is routing and that you're limited to CFX, SLI is only possible at 8x IIRC.
I think someone used one of those to connect a 980 to a NUC.
 

MarcWolfe

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Thats why Nvidia is retarded. 2 390s will work. Got a link for that NUC build? I've been wanting to do that.
 

spoki0

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Using M.2 to PCI adapter, as well as the PCI splitter, wouldn't that allow for a 3 way Crossfire on a Mini-ITX board?
Sounds like crazy over the top, but isn't that a bit what people do here?
 
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jb1

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Using M.2 to PCI adapter, as well as the PCI splitter, wouldn't that allow for a 3 way Crossfire on a Mini-ITX board?
Sounds like crazy over the top, but isn't that a bit what people do here?

Yep, it should, especially on an X99 board, because the M.2 lanes come right from the CPU rather than over the PCH. Think about it... you could have two GPUs at x8x8 off of the x16 port and then another x4 off of the M.2. The only thing keeping me from trying this in an Ncase M1 is the expense of purchasing 3 GPUs!
 
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chemist_slime

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I have this adapter and tried to hook up a graphics cards to it and didn't get any signal. Maybe I'm doing something wrong but it did not work for me unfortunately.
 

Demagolka

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For all of you with the Asrock X99E-ITX/ac motherboard. Have you tried an M.2 to PCIe adapter (like in this picture) with a PCIe riser for the second card? The Asrock X99 M.2 slot is PCIe gen 3 4x, thats plenty for a graphics card.
I have done this and it does work, though I haven't tried it with multiple GPUs. My goal is to fit an air cooled gpu and a 10gbe card into an ncase, but I also have a Samsung 950, so now I'm trying to figure out how to do this bifurcation thing.
 
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Schmov17

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Hey All,

Just stumbled across your thread today and this is great! I've been searching for concrete evidence of ITX Bifurcation for years. My project is slightly different, and I was hoping if anyone had any ideas/suggestions.

I'm trying to build a media server rig, with 2x RAID cards connected to a Mini ITX board. Both cards are x4 so bandwidth is no issue, but they draw power from the PCIe slot itself. Does anyone know if that would be a problem with any of those splitters?

Also, from reading through this thread, it looks like AsRock is the only consumer brand that has been proven to work with the passive adapters. Otherwise, an adapter with PLX should (in theory) work? Has anyone found any PLX adapters besides that SuperMicro one? I've got my eye on a Gigabyte board, but if it wont support a passive card I'll have to start looking for active ones, or see if I can sweet talk their support into trying to implement support.

Thanks!
 

Hermit2001

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I've been trying to find a bifurcated riser (side B / right) such as the Ameri-rack ARC2-PERY422 but they haven't been very responsive. Does anyone know of a good alternative?
 

jb1

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I've been trying to find a bifurcated riser (side B / right) such as the Ameri-rack ARC2-PERY422 but they haven't been very responsive. Does anyone know of a good alternative?

Haven't had too much trouble contacting them over email, have you tried calling them?
 

chemist_slime

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jb1: how's your build coming along? I recently picked up an Ncase M1 and might give it a try. Are you planning on using the same case?
 

jb1

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jb1: how's your build coming along? I recently picked up an Ncase M1 and might give it a try. Are you planning on using the same case?

Haven't made much progress lately–– I was actually thinking I might sandwich two ITX sized GPUs in Dondan's upcoming A4. The Ncase M1 is fantastic! You should be able to get everything working no problem in that case. At this point I think I'll probably wait a couple months and see if any GTX 1070's show up with short PCBs, like they did with the 970.
 
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