You must have 4G decode set, and have UIFI Mode set BEFORE you install Windows. Doing it after the fact will cause it to not boot.

So, just as an update - I did get all cards working properly last night. 7 GPUS, all firing now. What a nasty adventure. Here is what I can confirm worked.

Set PEG 0 and PEG 1 to GEN 1, 4G Decode "Enabled", Windows OS Configuration: Windows 8.1/10 "Disabled", Windows 7 "Disabled", Fast Boot "Disabled".  Reboot/shutdown.  Install one card at a time, rebooting between each card (not sure why, but worked for me) starting with x16 slot #2, then #5, 7, 1, 6, 4, 3.  If cards are modded you may have issues where screen won't post (board debug code may be 92-96, 97,98,99): in that case try installing a non-modded card in slot 2, and the modded ones in the remaining slots.  Alternatively, try OS Config...Windows 8.1/10 "Enabled" + with or without Fast Boot.

I used hacked drivers, but what is above is what did it for me. Hope this helps!

I just wanted to update the community - In the end, I did receive my order. That said, this company has the worst customer service that I've ever experienced. Not a single email of mine was ever responded to, until the day they delivered it.

My gut is that they never keep stock, and only order from their suppliers on a "need only basis" hence why it takes weeks to receive an order. They weren't too inundated with stuff that they couldn't accept the money transfer, but too busy to reply to my emails.

My two cents is avoid at all costs, unless you want things 3 weeks after they were ordered. Oh, and so people know - I live about 8hrs from their "store"

I can confirm that they offer crap service, but in the end I did receive my product.

I ordered 6 risers, and after that emailed repeatedly asking for an update as they claimed that the orders would be shipped same day.....In the end I received them 3 weeks later (I could have driven to them in 8hrs)

They only replied to me once they knew the delivery had been made. Total crap service, and would highly recommend avoiding them, but not a 100% "scam" site.

hrmmm, and I assume that all cards are over 2GB?

I've been at it about a week now with this board. I'm gonna make another effort tonight, so stay tuned. I'll report back here with my findings. All that said, its been a real ball ache, I could only imagine the BS involved with trying to use the M.2 connections. 

The "Cannot allocate big buffer for DAG error...." could also be because you haven't increased the Virtual Memory to 16GB

I can say with certainty that I DID have all 7 firing, and mining under Win10 w Claymore 9.6 - Then I screwed it up when I tried to flash one of the cards. Seems, based on what I read, having a modded card in slot 2 causes issues with the board not getting past POST - (board debug code may be 92-96, 97,98,99) - This has been a problem for me. I'll test tonight, and report back.

Cause all the cool kids are doing it, lol

Running into an issue with Windows 10 not properly detecting my cards, or not installing the drivers. Seems fine with 4 or 5 cards, 6 or 7 and it goes to junk. Also giving a Code 43 in some cases.

It was working the other day, all cards detecting, and showing up in Device Manager, but had to fool around some to flash a card. (card is working) so I know it wasn't the flash that is causing my issues.

I have to say, this board is finicky with 5+ GPU's....

Any ideas?

I moved the PCIE I was plugged into, and it started firing properly.
Once all drivers are set my intention is to use the integrated as my primary, but have had the best luck getting Windows to install drivers when I'm plugged into one of them.

Thanks for the response!

Hey Guys!

Hoping to get some assistance. I've re-read this whole thread a few times now, and can safely state the following;

7 x GPU's does work with the most recent BIOS but it is very important that you do the following BEFORE installing Windows 10.

UEFI only
Above 4G Decoding 'Enabled'
Win 8.1/10 set to 'Enabled'

You will otherwise run into grief. Once I did that, I was able to get Windows 10 to detect all cards.....but it isn't fully solved yet.

Right now I'm running the following;

MSI Z170A M5 Gaming board
G4400, 3.3 GHz Processor
8GB of Crucial Ram
1 x 1000w EVGA Gold PSU
1 x 650w EVGA Gold PSU
4 x Asus RX580 Dual 8GB
1 x R9 390
1 x MSI RX480 4GB
1 x MSI RX580 4GB

All cards are detecting in Windows, and I can fire up Claymore with stock settings (few of the cards have modded bios, but those particular cards ran solid for 4 days with OC prior to the addition of the other cards).

I'm currently using the most current drivers from AMD Drivers.

Long story short - I seem to be getting poor results from GPU0. All other cards are doing good given the lax settings, but GPU0 is only giving me about 4 or 5MH/s.

Any help would be really appreciated. This mobo has been one heck of a constant ball-kick though.

Same here - Placed an order, like an idiot - did the E-transfer, which they accepted within a few mins of me sending - No update, no replies to my emails, and sure as heck none of the "Same Day Express Shipping" they claim to offer.

Feels a lot like a scam to me, hope I'm wrong...

It would seem that either

a) they're overwhelmed with orders, or
b) they're scamming people.

Placed an order the other evening for a handful of risers, paid (stupidly) via e-transfer (they accepted within 20 mins), and now radio silence. Emails not being answered, chats not being answered. Nothing.

Beware of these guys, seems to be scamming.