Those saying Any cheap old cpu for mining Eth with this board, how many cards have you got working?

Also you're losing sata after 9 GPU's because you have ran out of cpu lanes, you'll need to turn off un-used
usb and sound resources via bios, to go higher.  If you're using a Celeron , 10 GPU's wil probably be max resources.

1 x PS/2 keyboard (purple)
1 x PS/2 mouse (green)
1 x HDMI
1 x LAN (RJ45) port(s)
4 x USB 3.1 Gen 1 (blue) Type-A,
2 x USB 2.0
3 x Audio jack(s)

Not any old CPU will do, when going above 10 gpu's.. So, if a Pentium with 4 threads can get 10 GPU's going, then...
I'll let you work the rest out..