Yes, they do.
Whether or not the motherboard manufacturer locks it down in BIOS is a different issue.
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PCIE Bifurcation
- Thread starter jb1
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Yes, they do.
Whether or not the motherboard manufacturer locks it down in BIOS is a different issue.
ionstorm66
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So I have an idea for a riser. I want to convert a single x16 into dual x8 low profile. I need to run a capture card and a 10G Ethernet. There are Atom and Xeon-D ITX boards with 10G, but they are all 1000 bucks. I can get a Asrock x299 + 8700X + Intel 10G for much less, with much higher performance.
I'm thinking a x16 stub with a flex going the the middle of the riser, and have the stub and riser bolted with a angle bracket. You need the flex, because one of the x8 slots has to be over the x16. There is a little over 20mm of height for the adapter if you stick a low profile card in a full height slot, from the bottom of the edge connector to the top of the pcie socket.
These adapters would be really nice for a lot of SFF setups. You can run a HBA/RAID, NIC, M.2, or even a low profile GPU.
Also a Bi/Trifurcating adapter that has a primary x8 and 1/2 M.2 slots, then you could run a 1050 Ti+M.2.
rfarmer
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https://www.gigabyte.com/Motherboard/Z370N-WIFI-rev-10#kf
Interesting, Gigabyte lists there new Z370 itx as having PCIe bifurcation support right on the webpage.
Interesting, Gigabyte lists there new Z370 itx as having PCIe bifurcation support right on the webpage.
Neapolitan6th
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Not often bifurcation support makes it next to the product name haha, good to see!
SaperPL & ZombiPL: How would you advise a Sentry owner to adapt your case to accept a PCIe bifurcation riser? Or is there a way to use one without cutting/modifying the Sentry at all (Perhaps with a bifurcation riser that provides two PCIe slots on each their own ribbon cable instead of both on a single board; C_Payne: does something like this exist or is it even possible)?
Context: I just got a Galaxy GTX 1070 Katana single-slot GPU. I plan to eventually get an Elgato 4k60 PCIe capture card. My motherboard already supports PCIe Bifurcation. Hopefully I can fit both in the Sentry without much issue.
Context: I just got a Galaxy GTX 1070 Katana single-slot GPU. I plan to eventually get an Elgato 4k60 PCIe capture card. My motherboard already supports PCIe Bifurcation. Hopefully I can fit both in the Sentry without much issue.
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Apparently now some Threadripper and Intel X299 (but only with a premium key, LOL) boards allow you to bifurcate x16 slots into four x4 slots and that allows the relevant Asus carrier board to be $55 instead of hundreds:
I'm not sure how you could handle the riser part here because Sentry is not designed to handle hard PCB riser and I don't think any ribbon riser with bifurcation will fit as those usually have the PCB part as well.
If you want to order a custom PCB riser to match the height of the slot gap in Sentry, you would need to use a custom straight extender that rises slot about 43mm or two standard ones that rise slot about 20.5mm (The standard gap between pci-e slots) but the latter wouldn't be precise and GPU would not be properly seated. As for the second slot, you'd have to either place the lower slot really close to the slot in the motherboard which would probably be quite challenging in PCB design or you would need to use flexible riser for the second slot.
For the mechanical part, as the capture card wouldn't be that heavy as GPU, you could simply get longer screws holding the riser and use two pieces of metal held onto those screws by nuts below the riser gap to imitate our riser holding mechanism for the second slot.
Note the fact however that Galax 1070 Single slot will have blocked exhaust in such configuration as it is blowing out hot air through the secondary slot and not through is own slot like reference blower designs. Note the perforation above the radiator and not so many holes in the slot that will be partially blocked by the bar between the slots inside chassis.
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Found it on Page 12, boy is that something. Not only will shorter cables be needed, but I'm probably going to have to hack at the Ameri-Rack adapter too—though the space in the Sentry is a little more forgiving so probably not that much. Thanks for the reference!
See MaximumBurrito's Dual Nanos in a Dan AT which Awilen referred me to above, maybe I can just do something like that?
How risky would it be if both the GPU and the other expansion card were to be held in place by only the GPU clamp/bracket of the Sentry case? If I'll be going by the MaximumBurrito build, which seems likely, the cards might just end up free-floating. You can see in one of his pics, he just uses a couple wine bottle corks to keep one of his GPUs propped up
That's a good observation, though I could get around this by swapping the positions of the expansion cards (just put the GPU in bifurcation slot #2 instead of #1) without losing much performance. Hopefully.
That's pretty sweet, but my m.2 slot is already occupied by an NVMe SSD and I don't want to have to cut a hole into the exterior of the Sentry to pass the HDMI port through. Thanks for the idea though, I'll definitely give it some thought!
The thing is, because of the IEC-C14 power connector location you might be really tight on space for mounting the risers to the PCB riser doing bifurcation. A4-SFX has a lot of space around the PCI slot in comparison to Sentry because it is bending the riser out there.
How risky would it be if both the GPU and the other expansion card were to be held in place by only the GPU clamp/bracket of the Sentry case? If I'll be going by the MaximumBurrito build, which seems likely, the cards might just end up free-floating. You can see in one of his pics, he just uses a couple wine bottle corks to keep one of his GPUs propped up
That depends on how will you use your PC. I wouldn't recommend carrying it around but when standing on the desk it should be okay. I would recommend however holding the second riser's slot as I described in my previous post.
We weren't making Sentry with such cards (blowing the air through their side) in mind and there's no end-to-end perforation on the GPU chamber bottom as well as there are no vents on the back of the case belo the PCI bracket. Because of that, there's a big chance you'd end up recycling hot air if you were to use your case horizontally. On vertical stand you might be okay, can't really be sure though...
You won't see an improvement in performance. The PCH is responsible for pretty much everything connectivity-related (USB, SATA, Networking, additional PCIe lanes...) and is connected to the CPU through the DMI (Direct Media Interface) 3.0, which operates at roughly PCIe 4x speed. That will be your bottleneck on Zx70 boards, up to Z370 even. This is the reason why on Z270, a RAID0 of high-end M.2 drives like the Samsung 960 EVO doesn't give very good scaling (http://www.legitreviews.com/three-intel-z270-platform-benchmarks-you-dont-want-to-miss_189763, with RAID0 of 950 Pro, bottlenecked at 3.3Go/s read speed with a theoretical maximum of 5Go/s. Those 3.3Go/s will go down as other activities on other ports want some of the bandwidth too.)
The architecture looks something like this:
CPU ------ DMI 3.0 (4x) ---- PCH (chipset) ---- PCIe and HSIO lanes ---- M.2, SATA, USB, Networking...
|
+--- PCIe (16x or 8x/8x) ---- GPU(s)
What you will see is an improvement in available connectivity, so more USB or SATA or M.2 ports, from upgrading to Z270.
The architecture looks something like this:
CPU ------ DMI 3.0 (4x) ---- PCH (chipset) ---- PCIe and HSIO lanes ---- M.2, SATA, USB, Networking...
|
+--- PCIe (16x or 8x/8x) ---- GPU(s)
What you will see is an improvement in available connectivity, so more USB or SATA or M.2 ports, from upgrading to Z270.
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Apathy_Enthusiast
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I've been using bifurcation for ~2 years now on my main PC, and trifurcation on a test PC, gotta say it's definitely the future.
Making a case for it, would love feedback from everyone in this thread: https://hardforum.com/threads/the-g-a4-layout-with-water-cooling-and-bifurcated-riser-15l.1948544/
Also planning a small version ~8L similar to DAN A4 with bifurcation.
TheArkratos
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Everytime I asked them I got a "I don't know, ask [Someone else]" and eventually would get to someone that just wouldn't answer... So good to finally get an answer, annoying that it's a no.
TheArkratos
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Does anyone know of a riser that isn't single slot spacing?
I had their USB 3.0 SDI (uncompressed video) capture adapter, and it worked pretty well (1080p60). I like how they provided a SHD connector to HDMI cable for this m.2 adapter... wouldn't be hard to mount.
I think I should cross post this here:
Neapolitan6th
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Wow, very clean! Fairly easy to do too. Shame about taking the dremel to such a beautiful case though.
The way he he cut out this piece off makes it still feasible to put it back together - in Sentry you are actually tightening those two metal lips on the riser's plastic body, so he can screw this back together, but it won't be rock solid as it was initially though.
Yeah, I had a really hard time coming to that decision; I attempted all sorts of different ways of fitting the bifurcation riser in the space between the GPU motherboard compartments, and just running the supplied riser cable through; I even came close, unfortunately there was just too much slack in the riser cable lengths to shove without risking damaging anything. It could possibly be done with a right angle PCIe adapter and custom riser boards, similar to the one C_Payne made for the RVZ01.
I was also thinking I could possibly put it back together with some scrap aluminium and rivets if I ever decide to undo the whole thing, but considering how well the mod currently works I might just try to screw/rivet the bifurcation riser to the Sentry instead. You guys built this thing solid like a tank, and there's actually more room than one would initially think to do some work in there (I had no idea the Ameri-Rack riser I bought would fit the way it does, I was prepared to have to do much more drastic modifications), so I actually don't feel very limited in the options I have.
If I remember correctly, the slot bifurcation supports configs of 8+8 or 8+4+4 as there are only 3 device controllers attached per x16 slot - you can see it here:
You should be able to split that into more with some advanced riser but I'm not sure if GPUs will work on such split. Those boards having multiple x1 slots for mining are custom built for that and probably have some bios hacks to overcome standard limitations.
You could use something like this: https://www.aliexpress.com/item/1-t...n-Cord-PCI-E-16X-turn-8-Port/32827248418.html
You could combine two of these with x8x8 bifurcation to get 16 GPU's with x1 lane speed each.
If you want to go full bonkers You could also combine this with 16 of these https://www.aliexpress.com/item/NEW...s-16X-slots-Riser-Card-PCI-E/32812873421.html
64 GPU's with 1/4th lane speed...
Another 64 splitters and you get 256...
Maybe you will eventually run out of address space???
It looks like this card uses 4X lanes of signal while the connector is 16 lanes wide:
So You might be able to go with 4 of those somehow? But if there are 8 pci-e X1 lanes using pci-e X4 slot connection then there has to be some queuing on the bus to do this.
This one looks to be doing a bit more extreme queuing on the pci-e bus, I wonder if stacking those wouldn't make the system kill the device driver when the bus is loaded due to increased latency thanks to the amount of queuing. I wonder If the manufacturer handled that possibility.
Hey guys,
Found this thread a thrill to read. Wonder if Bifurcation could help me if its even supported on my MSI Godlike X99A motherboard. Heres the deal got two 980Tis both at 16X link speeds thanks to a 6850K CPU seated in PCI slot #1 + #4. Got a M.2 NVME Samsung 950 Pro on the M.2 onboard connector that shares bandwidth with the last PCIE#5 slot. If I connect another PCI-E NVME drive into slots 2 or 3 my gpus bump down to x8 speeds. I know real world not a major deal but I paid for lanes and want x16 on each GPU. So according to the lane distribution map for my board the bottom half of the pcie lanes on the PCIE#5 slot are not share by anything and to avoid my M.2 onboard Samsung 950 from downgrading I need to isolate that last 4X lanes of slot #5.
Problem is I'm not sure MSI supports bifurcation or not on slot #5 or if its even possible with a dual m.2 x8 card. Read using 2nd m.2 slot is ignored. Anyhow this makes me wonder if theres a setting in AMIBCP that I can play with to enable bifurcation if the manufacturer did not enable it by default. Looked under the hood and there are a lot of PCI-E settings. Since this is getting dangerous at this point I defer to your best judgement.
Thank you.
Found this thread a thrill to read. Wonder if Bifurcation could help me if its even supported on my MSI Godlike X99A motherboard. Heres the deal got two 980Tis both at 16X link speeds thanks to a 6850K CPU seated in PCI slot #1 + #4. Got a M.2 NVME Samsung 950 Pro on the M.2 onboard connector that shares bandwidth with the last PCIE#5 slot. If I connect another PCI-E NVME drive into slots 2 or 3 my gpus bump down to x8 speeds. I know real world not a major deal but I paid for lanes and want x16 on each GPU. So according to the lane distribution map for my board the bottom half of the pcie lanes on the PCIE#5 slot are not share by anything and to avoid my M.2 onboard Samsung 950 from downgrading I need to isolate that last 4X lanes of slot #5.
Problem is I'm not sure MSI supports bifurcation or not on slot #5 or if its even possible with a dual m.2 x8 card. Read using 2nd m.2 slot is ignored. Anyhow this makes me wonder if theres a setting in AMIBCP that I can play with to enable bifurcation if the manufacturer did not enable it by default. Looked under the hood and there are a lot of PCI-E settings. Since this is getting dangerous at this point I defer to your best judgement.
Thank you.
Did you look through the bios to see if there's a config for each slot to see how it's set up electrically? I recall that some boards having secondary pci-e x16 slots that are electrically 8 or 4 have configs to switch between x1/x2/x4 etc. Your board might have it set up as x8 by default and when you plug in any device it might reserve all those lanes regardless of the device using only 4 lanes for some reason.
Do you have a sata express drive connected by any chance? It's also included in the PCIe Bandwidth Table of your manual. If yes, then this might be a reason why plugging another M.2 drive cuts down your lanes.
Did you try connecting your main drive into the pci-e slot instead of the on-board M.2 slot? You could see then if you'll still have the same amount of lanes for your GPUs.
I think that dual M.2 card should work for you in slot #5 as this would be just as the manufacturers 3-way configuration in PCIe Bandwidth Table of your manual.
Do you have a sata express drive connected by any chance? It's also included in the PCIe Bandwidth Table of your manual. If yes, then this might be a reason why plugging another M.2 drive cuts down your lanes.
Did you try connecting your main drive into the pci-e slot instead of the on-board M.2 slot? You could see then if you'll still have the same amount of lanes for your GPUs.
I think that dual M.2 card should work for you in slot #5 as this would be just as the manufacturers 3-way configuration in PCIe Bandwidth Table of your manual.
Could be possible.
Proper BIOS Hacking is something this Topic is really in need of, to enable bifurcation on different boards.
I take it you have a dual m.2 to pcie x8 adapter on hand? Like this one?
You could try to keep one m.2 in the mobo m.2 slot. Then isolate the #prsnt signal on your x8 adapter (eg. with some tape)
Now try both riser m.2 slots (start with the top one) Maybe you can trick your mainboard this way.
Proper BIOS Hacking is something this Topic is really in need of, to enable bifurcation on different boards.
I take it you have a dual m.2 to pcie x8 adapter on hand? Like this one?
You could try to keep one m.2 in the mobo m.2 slot. Then isolate the #prsnt signal on your x8 adapter (eg. with some tape)
Now try both riser m.2 slots (start with the top one) Maybe you can trick your mainboard this way.
No I do not own a dual m.2 adapter. I was thinking of getting one or even better a pcie two slot extension adapter because my second drive is a Plextor AIC M8pey Pci-e Card (not a stick) unlike my Samsung 950 Pro which is now giving me 700 mb/s max seq read speeds where before it was like 2200 mb/s. In any case I also have a two drive Samsung 850 sata raid 0 running off of sata ports 1 + 2. I think that is eating the bandwidth as with dmi 2.0 specs your allowed max 2000mb/s bandwidth from the pch including sata, usb, and other devices.
What was really cool though was that I was able two unlock two additional bios menu settings with Amibcp last night.
1. CPU LANE ALLOCATION - either 8/8 or 16/0
2. M.2 MODE - Pcie cpu, pch cpu, sata, sata express, and pcie 8x modes
Selecting anything but pch mode caused the Plextor drive to disappear. So at this point only solution would be to plug the Plextor in a free slot between the Gpus forcing one of them to 8X. No big deal but aesthetically feel short changed. Perhaps with a pci-e two slot adapter and riser cable something might work?
Thanks
What was really cool though was that I was able two unlock two additional bios menu settings with Amibcp last night.
1. CPU LANE ALLOCATION - either 8/8 or 16/0
2. M.2 MODE - Pcie cpu, pch cpu, sata, sata express, and pcie 8x modes
Selecting anything but pch mode caused the Plextor drive to disappear. So at this point only solution would be to plug the Plextor in a free slot between the Gpus forcing one of them to 8X. No big deal but aesthetically feel short changed. Perhaps with a pci-e two slot adapter and riser cable something might work?
Thanks
Could you describe what exactly did you change in your bios. I am so far not familiar with amibcp.
I have checked 6950x datasheet. It tells me that bifurcation to x4x4 of that port is supported. However I really wonder why MSI did not implement it.
That datasheet also states support for x4x4x4x4 bifurcation on the x16 ports and the x99e bios for example only supports configuration to x8x4x4. Maybe the AMI APTIO V is not capable of configuring that. Or the Datasheet is erratic? I will dig deeper.
I have checked 6950x datasheet. It tells me that bifurcation to x4x4 of that port is supported. However I really wonder why MSI did not implement it.
That datasheet also states support for x4x4x4x4 bifurcation on the x16 ports and the x99e bios for example only supports configuration to x8x4x4. Maybe the AMI APTIO V is not capable of configuring that. Or the Datasheet is erratic? I will dig deeper.
Yeah sure. Its the last two items I was able to add to my bios menu. Gives a little more fine control over the M.2
settings of which would normally be set automatically by the motherboard:
In any case if you guys could settle a point of fact. The guys at MSI forum are saying that in regards to Bifurcation support it has to be hard wired onto the motherboard and no simple bios update will enable that. Is that true? I thought it could be done through bios modification from reading the Asrock reports?
Thanks
PS: There a couple other PCIE bios settings as well.
settings of which would normally be set automatically by the motherboard:
In any case if you guys could settle a point of fact. The guys at MSI forum are saying that in regards to Bifurcation support it has to be hard wired onto the motherboard and no simple bios update will enable that. Is that true? I thought it could be done through bios modification from reading the Asrock reports?
Thanks
PS: There a couple other PCIE bios settings as well.
So it’s software controlled? If so then you could theoretically change a dummy bios setting item and enable this feature if you know how to read machine code and understand registers and memory addresses. Unfortunately out of my area of expertise. If only Revogirl was here.. sigh..
