I have 9 hooked up to it. The ones that are working run rock solid more or less, at least as well as they did on W7, but three just give nothing but Comms Errors. It is vaguely similar to a problem I had with cgminer versions after 2.3.6 where I could not run all nine in the same instance, and had to split it into 6 & 3. I may try that later today.