FINALLY got this working with > 4 GPU
OS: Windows 10
After days of struggling to get this working I tracked down the issue.
Normally I'm looking at the Device Manager application listing for any issues with devices. The devices were all listed. The devices when I right click and say update driver would state that it has the latest driver.
So nothing seemed out of line there. But system would not let me use 5 cards, sometimes just shut down and auto reboot.
Finally I went into the System Information > Problem Devices
Here listed were all of my cards as having driver problems.
I went back into the Device Manager and uninstalled all of the GPU devices except for the primary one, then rescanned for hardware changes. Took a few minutes, then selected device and updated the driver. The system took a few minutes to get these done but now I can see all 5 cards and am able to mine with the 5 cards I have.
Hope this helps someone.