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System components:

MSI 970a-g43
FX-4350
2x 4GB DDR3 RAM

GPUs:
6x GTX 1060 3GB
1x GTX 1080ti

PSUs:
1x Seasonic Focus PLUS 850W (secondary)
1x EVGA G2 850W (secondary)
1x XFX 550W (primary, powers the motherboard+CPU+drives)
(All graphics cards are powered by the same PSU that powers their riser, if one is used.)

OS: Windows 7 x64


https://images10.newegg.com/NeweggImage/ProductImage/13-130-679-07.jpg
I am attempting to get the following configuration to work:

(Slots ordered by increasing distance from the CPU)
PCIe x1:
One powered riser to a 1060 (powered by the EVGA)

PCIe x16:
One powered riser to a 1060 (in every case that the system booted, this card in this slot was used for the display, as is expected) (powered by the XFX)

PCIe x1:
One powered riser to a 1060 (powered by the EVGA)

PCIe x16:
The following 4-to-1 splitter, with 3x 1060s and 1x 1080ti installed:
https://www.amazon.com/Ubit-Riser-Adapter-Powered-Extension/dp/B0746H1KY3/
The 1080ti and 2x 1060s powered by the Seasonic, the last 1060 by the EVGA.




Each time I attempt to boot with all 7 cards connected, no graphics output is shown on the monitor.

Even more confusing, after reaching a stable configuration with 6 cards (6 can seemingly be reached with any combination of cards and risers), and attempting to boot with a 7th card connected, something gets munged. When I undo the addition of the seventh card, I find that I can no longer boot with 6 cards, a configuration that had just previously worked. Clearing CMOS at this point, does not help.

I find that I can only boot again with 6 cards after going back to 5 cards, clearing CMOS, booting to Windows with those 5 cards, shutting down, and then adding the 6th card before booting once more.



Previous stable configuration, before attempting to install the 1080ti (again, in order of increasing distance from the CPU):

PCIe x1:
One powered riser to a 1060 (EVGA)

PCIe x16:
One 1060 installed directly onto the motherboard (XFX)

PCIe x1:
BLOCKED by the card installed in the previous slot.

PCIe x16:
The aforementioned 4-to-1 splitter was used with 4x 1060s. (All of which worked flawlessly.)
3 powered by the Seasonic, 1 powered by the EVGA.


Additional notes:

I've tested each of the graphics cards, risers, and PSUs individually. The BIOS for this old board is the latest available (with no settings for 4G decoding or PCIe link speed).

I do not believe that the 4-to-1 splitter itself is the problem, as it still works with 4 cards connected to it.

I've been stumped on this for quite some time now, so I'm about ready to accept that 6 cards is as far as I can expect to push this motherboard. Any advice is greatly appreciated!

Hi,

I have the same board and I'm planning to add more GPUs to it and was wondering if you were able to run it with 7 GPUs?

Did you try Win10 and enabling the IOMMU in BIOS?

Thanks!

I don't like the adaptor idea for the GPUs, it would have been better I the motherboard have up to 7 pcie slots on its own instead of using adaptor, also make sure your power supply can power all the GPUs at once, calculate the power draw of each cards and also the watt of the motherboard, also update motherboard bios, that may help, if none of this works you will need to get a separate motherboard

You can't use more than 4 graphic cards in this motherboard, why forcing things out? Come to think of it the pcie slots can only deliver or supply a certain amount of watt so adding extra adaptor won't work so well, better go out and buy better motherboard that suits your need

I can think of 2 possibilities.

Power is always suspect. Three smallish PSUs is probably not the best way to go.

The other is PCIe lane sharing. Most mobos share PCIe lanes when multiple slots are in use.
The first PCIe x16 slot probably can't use all 16 lanes when the second x16 slot is also in use.
Maybe the adapter needs all 16 lanes to be avalable to do a x4,x4,x4,x4 split.
Check the mobo documentation for lane assignment.

If you are going to use an adapter make sure you aren't using other available slots for any other thing, the whole GPUs are going to be powered through a single pcie slot with the adapter, also why not run just 6x GPUs on that motherboard? I think more than that can cause problem or stability issues 🤔

In modern mining, we use powered riers .... so the power come from the risers not the slots.

yep thats correct it is called powered risers :)
i tried this adapter but different mobo (h110 d3a from gigabyte) it works no issues.