@crucifier - that is why I asked, please link some board or BIOS you know this is in so we can check. If there is discussion of some beta, link that BIOS, it may not be on regular motherboard download page, you’ll have to find it where they are discussing it.
I think what you mean, normal lane split for SLI/XFire is not same thing as bifurcation. Maybe it is and I’m thinking about that wrong?
I see these options at ME @davidm71 - do you think changing here helps anything (Default in blue) I’m digging around in assembly right now @AMITSE and Setup, but nothing looking interesting there, maybe since non-optional in BIOS I need to look at some PCH or SA module instead.
I think there is only one way to split PCI-e lines without additional PLX . The way in which these lines are directed to physical slots matters, though.
That’s normal for PCIE slots, even P35 and earlier did that, I don’t think that is same thing unless I’m reading you wrong. Do you mean If one card is in slot 1 it’s x16, then if you connect second card in slot two, both slots become x8, is that what you mean? If yes, I think that’s not the same thing as an individual slot becoming x8x8 or x4x4x4x4. Or did you really mean from a single slot you are getting x8x8 across two drives?
Yes exactly. In my opinion, in this case, if all the lines remain in the same slot, it will be bifurcated. If the mobo sent half the line to another slot, there are no big differences, since the PCI-e controller is still in the CPU and configured through the chipset to work with two devices with 8 lines each. The bifurcation is solely how configured PCI-e controller to one or more devices accross lines.
I could be wrong, so this is just how I understand this process.
But in the case of h87, for example, no one mb can break lines without using a PLX chip, since bifurcation is not supported in the chipset. The processor works with x16 lines as one device, no matter how many lines the device can handle - no SLI possible.
I thought that’s what you meant the way you mentioned it, that isn’t bifurcation, at least not in the way we’re talking here. Bifurcation is on a single slot only, not changing whether it’s x16 or x8, but making one single slot x8+x8 by itself (So still x16) or x4+x4+x4+x4 (still x16 total)
PLX Chip is normally used to add more lanes than the CPU/Chipset has, for SLI/Crossfire, this isn’t added for bifurcation either, but I supposed it could be used in that way. @paranoid_android was having issue with bifurcation on P9X79 due to PLX, I think, or at least it was messing with things more-so than his other similar board without the PLX
So, you don’t know any BIOS from Asrock or MSI from Z97 that you’ve seen someone confirming bifurcation for PCIE SSD’s?
No, I can’t find any direct link for z97 with manual bifurcation settings in BIOS.
I think it act as a hub and can’t to add any lines, only split one x16(for example) device to several devices with less bandwith. But PLX can do it without any cpu, chipset compatibility issues.
Not sure because I am sorry to say I am not familiar with ME?
FWIW when I bifurcated my 16x lane into 8X 8X I had studied the board layout and circuit analysis review showing the physical lane tracings on the board going from a Pericom PI3PCIE switch to the second end half of the pcie slot. So I already had a switch that’s was turned off by default. So not only did I have internal bios support via setting those variables I also had physical support on the motherboard. Thus using a Supermicro 8x8x adapter allowed me to access those later physical unused lanes.
So if your going to try to bifurcate a 16x slot into 8-4-4x config on haswell chipset or z97 going to need physical support or something like that Supermicro card with 8-4-4 slot layout with switches built in if not on the motherboard and support via variables or registers or whatever. Sorry to say I haven’t read the documentation to tell further but only way to tell if changing those strap settings does anything is to experiment. Not familiar with that utility?
Thanks @davidm71 - I guess only way to know is try changing some things That is Intel FITc, from the Intel ME System Tools packages, that you do the ME clean/transfer with from the ME Cleanup guides and ME Drivers/System Tools thread. Does any of the others look like they’d be ideal, aside from the one highlighted in blue (That’s the default applied value)
@crucifier I thought you said you knew users/threads where this was being shown, discussed, used etc on Asrock/MSI Z97 boards? I’ve not seen it possible on Z97, but people don’t often look into this on older boards either, but they few I’ve looked into lack the basic BIOS necessities to enable.
Thank you for your attention to my request for help. It is very interesting to dive into the BIOS functionality and configuration, but in this particular case it is not economically efficient. I’m going to buy a used motherboard with an additional slot and support for x8x4x4 bifurcation for $ 50-80, that will be easiest way.
Hi David, Thanks for your guide, I’ve been reading it over and over for the last few hours.
I have a ASUS X99 SABRETOOTH Currently on a 28Lane CPU (x16,x8,x4[/m.2]) (all 16x physical) will be upgrading to a 40Lane in the future. I have my GPU in slot 1 x16. Then an m.2 boot drive in the x4.
I ordered an ASRock Quad m.2 card to put in the x16 Slot 2 (x8) works great but only the first m.2(1) port works because of bifurcation.
I have already found out my settings in the BIOS Mod can be set to x4,x4,x4,x4 which I’d like to apply to 16x slot2. Which while I have a 28Lane CPU in there should work as a x4,x4 slot.
What I was missing from your guide was the reasons why I needed to change some of the other things like loading up the RU utility, I couldn’t work out what I was supposed to be changing.
PCIe Slot 3 is already bifurcated on this board.
After writing all this just realised I missed a bit of the guide that said this just stores things in RAM before writing your bios to check.
Personal Notes: IOU0 0x533, 0x534, 0x535, 0x536 (well that’s easy to remember.) I wanna change these to 00 for x4,x4,x4,x4
Glad you enjoyed the guide. Not really familiar with your motherboard PCI-E lane allocation scheme.
In my case my board had an extra 4 lanes that went to waste with a 40 lane cpu. I had noticed that those extra 4 lanes were on the 2nd half of my last pci-e slot that shared bandwidth with my m.2 so I had to bifurcate that slot to take advantage of those last four lanes or else you were just buying a 36 lane cpu!
Any how the reason why I used RU.EXE was because I needed to make minor changes here or there to my bios variables and I didn’t want to reflash the board every time. Changes included in the PCI-E timeout values and sync settings that were necessary to help provide a true 8x 8x bifurcation because sometimes the board would fail to sync and down negotiate the speed to 2x or 4x.
Fwiw I’m back to using stock bios for time being because my motherboard started to act weird since one of my gpus died a few weeks ago. Long story…
The Three 16x slots Labeled 1, 4, 6 run at x16 x8 and x4 respectively, as I only have a 28Lane CPU instead of the 40Lane one, If I had the 40 it’d be (x16, x16, x8(shared with the m.2)
I used RU to set IOU0 0x533, 0x534, 0x535, 0x536 each to 00, when I rebooted into windows I still had only 1 x8 device running at x4 which was my 960evo which is sitting in the ASRock Quad M.2 https://www.asrock.com/mb/spec/product.a…AD%20M.2%20CARD
So the RU modification didn’t take. I did a reboot and checked that the bits had been fliped, back into Windows and no change looking at HWInfo
I’m open to suggestions, apart from buying an X299 I don’t have the money for new board and CPU
1. Not using the right kind of m.2 card. I used a supermicro server based card in my case.
2. Bifurcation depends on having a physical switch on the motherboard or accessory card for it to work such that in my case there was an unused switch on the motherboard that I think helped me bifurcate. These switches look like a black transistor on the motherboard and every two slots got a couple. This is what signals the board to switch from 16x to 8x when a second card is installed.
Also are you sure in RU your working on the correct section? You should be working on Intel Setup module corresponding to your IFR breakdown.
Edit I looked at your motherboard breakdown of lane allocation and I think you should at least be able to do the same exact mod as I did if you have a 40 lane cpu.
Not sure about being able to use a quad m.2 card would work. Those are proprietary and takes a lot of experimenting with different cards to get it to work.
Hardforum has a bifurcation thread you should check out.
Does this mean that the boards that this QuadM.2 Card are compatible with have some special switch upon the x16 lane they go in that alters them to x4x4x4x4?
The BIOS Modifier shows that the two x16 can both be split, to x16, x8x8, x4x4x8, x8x4x4, x4x4x4x4.
Okay quick update, decided to go for broke and enabled PCIe Slot 1 (the main x16 slot with my GPU in it) into x4x4x4x4 mode. Ended up with 3a,3b,3c,3d and my GPU is sitting pretty in a x4 enabled slot.
I moved my ASRock Quad m.2 card to the top x16 slot and moved my GPU down to my second x16 slot (running at x8). I’m going to suffer with GPU performance but it has proved my hypothesis that it does work. I think because I have a 28Lane CPU installed it’s Pre-Bifurcate the second slot and turned off the last x8 lanes so the motherboard doesn’t have an option for just x4x4.
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That is Intel FITc, from the Intel ME System Tools packages, that you do the ME clean/transfer with from the ME Cleanup guides and ME Drivers/System Tools thread.
