For Windows 10 to add 12-13 GPUs or more, just update to 1709 version. To check Windows version Run>winver and update GPU driver to latest version.

https://scontent.fbkk9-2.fna.fbcdn.net/v/t1.0-9/27332048_10155032683387307_7733597976880691189_n.jpg?oh=7bca63b822b75a7c21e4219519900a5d&oe=5AE420DD

This is mine.
https://scontent.fbkk9-2.fna.fbcdn.net/v/t1.0-9/27067632_10155032690897307_5682416157259787655_n.jpg?oh=60ca20026d9867bdfd0fa11b1293a61d&oe=5AE188D1