I tested out the BTC B250C Motherboard with 12 Nvidia GPUs in Windows 10 and it is a great board!
See more details and get one here:
https://cryptomined.com/index.php?main_page=product_info&cPath=240_394&products_id=383

Components I used for this test build:
Motherboard: BTC B250C
Ram: 4G DDR4 Adata
CPU: Celeron G3900
PSU: Various EVGA G2 PSU’s
GPUS, Various 1070ti, 1080ti and a Titan X (Pascap)
Risers: Various Sata and Molex Risers
SSD: 120GB Galaxy SSD

Need an NVidia GPU? These are instock on amazon or soon to be in stock

GTX 1060s in stock:
EVGA GeForce GTX 1060 SC GAMING
http://amzn.to/2HsFRgi

Gigabyte GeForce GTX 1060 Windforce OC 3GB
http://amzn.to/2FOZAtv

EVGA GeForce GTX 1060 3GB GAMING
http://amzn.to/2DjUfF7

ASUS GeForce GTX 1060 6GB Dual-fan OC
http://amzn.to/2pawcEv
UK: http://amzn.to/2Fze2Cd

MSI GAMING GeForce GTX 1060 6GB
http://amzn.to/2HtMhM5

GTX1070s in stock
MSI Gaming GeForce GTX 1070 8GB
http://amzn.to/2FBr3eG

ASUS GeForce GTX 1070 8GB ROG STRIX OC
http://amzn.to/2FIkzOm

ZOTAC GeForce GTX 1070 Mini 8GB
http://amzn.to/2Gk2X9m

Gigabyte GeForce GTX 1070 WINDFORCE OC 8G
http://amzn.to/2tDuiAT

1070ti instock
MSI Gaming GeForce GTX 1070 Ti
http://amzn.to/2FAWZjr

MSI Gaming GeForce GTX 1070 Ti
http://amzn.to/2GkOoT8

MSI Gaming GeForce GTX 1070 Ti
http://amzn.to/2GjXvmY

1080ti in stock
ASUS ROG STRIX GeForce GTX 1080 TI
http://amzn.to/2Dkrlon