I only have 7 580's so I can't say if 8 card limit on Windows is Removed but I installed 1709 and the drivers dropped the cards dropped to 24MH. Some things I found:
- Using Autologin my start button and action center do not work
- Task manager now shows GPU stats on the perf tab, all 7 GPUs are there which is neat
- I had to DDU a few times to get block chain drivers to stick, Windows kept auto installing even when set not to, I finally set with GPO, not sure it that was needed but it is working now
- I cannot shut down the computer anymore even with power button, it just bounces back to logon screen, restart works fine

Has been completely stable mining 24 hours now