Cannot get 8th GPU working on Windows 10 rig

[labsy]

Hi,
I've build up mining rig on MSI Z270-A with 8x Nvidia 1070Ti GPUs. I stuffed some of GPUs into PCIe slots with risers, and the rest into PCIe-to-USB 4x riser.
But regardless of which GPU I stuff where, I can only get to 7 GPUs being recognized by Windows 10.

Updated Windows 10 to latest, patched nVidia drivers to latest, removed and reinstalled them fresh, removed all cards and tried different combinations, stuffed them in one-by-one into different slots, tried 5 risers + 3 in adapter, 3 risers and 4 in adapter and 1 to M.2 adapter, tried different PCIe slots...but still cannot get Win 10 to recognize 8th GPU.
And it's not particular GPU/riser/cable, but ANY GPU which I add as 8th is not recognized.

Is there anything I missed in BIOS?
Of course, I have "Above 4G" ENABLED, UEFI Enabled, Win 7 Disabled, HD Audio DISABLED, COM and LPT ports DISABLED.
I have also DISABLED integrated Intel graphics adapter. But still no joy.

Maybe anything to do with "PCI Latency timer" which can be set to 32, 64, 128, 196, 224?

Ideas welcome.

[1715671094]

1715671094

[1715671094]

1715671094

[1715671094]

1715671094

[philipma1957]

I asked mods to move this to alt coin.

what is the number of your win 10 build?

I think it needs to be build 1709

[labsy]

I asked mods to move this to alt coin.

what is the number of your win 10 build?

I think it needs to be build 1709

Thank you for suggestion on moving to Altcoins. My bad choice of forum.

Regarding Windows 10 build...it is 1709, patched to the today's  latest.
Nvidia drivers 391.01, also fresh.

Hmmm...I have SSD on M.2 slot. Might this one take the last PCIe line, thus not being able to run 8th GPU?

[jmigdlc99]

Do you need to run your SSD on the M2 slot? You may be right and that could be it.

But i'd first try to swap out the riser and cable if you've got a spare one. Could be just a faulty riser or loose connection.

[labsy]

SOLVED! Finally
First I had to clone OS from M.2 disk to SATA SSD disk to free up PCIe lane. That was the catch.
Then I pulled out all GPUs, ONE BY ONE to determine, whether it is the catch on PCIe slot or on PCIe-to-USB adapter. And it was PCIe! Simply could not handle more than 3 GPUs directly attached to PCIe slots.
So I used:
- 3 GPUs via risers directly attached to mobo
- 1 GPU via M.2 PCIe adapter
- 4 GPUs via PCIe-to-USB adapter
Plugged in then 1-by-1, rebooted and WAITED few minutes after each reboot, until Win10 settled down. If GPU was not found, rebooted again. After 2 hours rebooting and plugging-in finally all 8 GPUs running

[Swinging Phallus]

SOLVED! Finally
First I had to clone OS from M.2 disk to SATA SSD disk to free up PCIe lane. That was the catch.
Then I pulled out all GPUs, ONE BY ONE to determine, whether it is the catch on PCIe slot or on PCIe-to-USB adapter. And it was PCIe! Simply could not handle more than 3 GPUs directly attached to PCIe slots.
So I used:
- 3 GPUs via risers directly attached to mobo
- 1 GPU via M.2 PCIe adapter
- 4 GPUs via PCIe-to-USB adapter
Plugged in then 1-by-1, rebooted and WAITED few minutes after each reboot, until Win10 settled down. If GPU was not found, rebooted again. After 2 hours rebooting and plugging-in finally all 8 GPUs running

Good, I'm happy for you. Thanks for actually posting the results after you resolved it. More people oughta do this, it's useful to anyone else who stumbles on the thread.