Hello.
I use 7 MSI GTX 1060 3G on Biostar TB250 with M.2 adapter and all 7 cards are detected and works fine 170 MH/S at 620W power (with +800 MHZ memory overclock MSI Afterburner). The secret is: BIOS update.
Good luck.
Can confirm, 7 cards are detected, and installed in windows but while mining CPU usage will rise to 100% and miner crashes coz of hardware/interrupt errors.
M.2 slot works with Nvidia GPU's, does not work with AMD GPUs.
Update : Working with AMD cards as well.
Please can you help me getting my TB250 working with a 7th GPU with M.2 pcie adapater, I can´t getting to work, can you change something in mobo bios configuration? I have last bios version.