I also bought this board assuming it would run 8 cards
Fact is, I did get 8 cards up and running, but it was unstable, the 8th card kept falling off, and even with 7 cards running, my rig crashed way too often to make it worth the trouble. This is on Windows 10.
I do, though, have six cards running and all appears to be stable. I went to bed last night with six 1080TI cards crunching ZEN and it is still running now, about 10 hours later, so at least a stable six-card setup is possible, even if you can't get the m.2 slots to work reliably, though it is also possible that I just got semi-lucky.
It wasn't easy. I had to go through quite a lengthy process to get it going. Here's what I did:
First, go through the standard motherboard BIOS modifications. Without BIOS mods, this won't work.
Next, with the CPU to the left, label the six PCIe slots 1 - 6. I added one card at a time in this order: 1-4-2-6-5-3. Crazy but this is what it took. The manual says the full sized slots should be used first left to right, but that didn't work out for me. After each card was added, I would check the device manager to make sure they were all recognized without error. If I had an error, I would reboot without the last card, then reboot again after adding the new card to a different slot. That's how I ended up with the 1-4-2-6-5-3 progression. Your progression may be different than mine.
Finally, to get the 7th and 8th cards "running", I used the m.2 slot to the right first, then the one next to the CPU. Again, not what you would expect, but that's the way it was for me. Ultimately, I removed both m.2 adapters anyway. I did get lucky and bought the white explomos adapters (looks just like the Lattcure ones from Amazon UK, so I assume these are the US version), which appears to be important to have any shot of cards 7 and 8 working.
After each card was successfully recognized by Device Manager, I also powered down and booted up two or three times before adding another card. I could tell by differences in each boot procedure that my computer was still sorting out the new card. After three or so boots, it was reliably repeating the standard boot procedure and I moved on to the next card.
Important: My rig looked like it had locked up several times during the process. It was simply working at sorting all those cards out, and it took a very long time. After adding each card, if your screen goes blank, the monitor goes to sleep, the circle of dots on the login screen freezes, etc.......just go take a walk or something. Don't mess with the power button. Leave it alone and let it do its thing.
Finally, this is all relevant if you own this board and can't return it and have no other options. Do not buy this board for mining if you don't already have it unless you hate yourself.
