2 out of 3 PCI-E x1 Slots not working on MSI Z270 PC MATE (Solved)

Hi guys,

I’m trying to run x4 GTX 1080Ti cards on MSI Z270 PC MATE m/b on Windows 10. I’m using USB powered risers. I was only able to run 3 cards on slots 1,4,5. It seems that slots 2 and 3 are not working.
The m/b has 5 pci-e slots
slot 1 pci-e x16
slot 2 pci-e x1
slot 3 pci-e x1
slot 4 pci-e x4
slot 5 pci-e x1
I have tried to run only one card on each slot at a time. Card in 1 or 4 or 5 - pc posts to windows with no problems. Slots 2, 3 just black screen.
I have tried the following:

  • swapped risers
  • flashed BIOS to latest version
  • switched between gen 1, gen 2 in BIOS. Also toggled 4G/crypto mining option on/off.
  • turned off on board audio, integrated graphics set to PEG (PCI Express Graphics)

I would greatly appreciate it, if anyone has any ideas what else can be done here. My last reserve would be to RMA the m/b. Thanks!

Update:
Decided not to wait and ordered same board from amazon with free next day shipping. Installed the board today and all 5 slots work. Will be RMA’ing bad board back to newegg.

Thanks for following up; congratulations on your success! Welcome to the race.