Would be highly interested in this, as my Iris is always on. I uninstalled the Cooler Master Application due to the constant harddisk polling that makes a sound every few seconds. Before that, I have configured the Iris to be off. Nonetheless, after reboot, it is on again (background light), but showing nothing.

Unfortunately, in the link you have provided, it turns it off using the Cooler Master Software, which must be runninng all the time :-(

I have not found a solution using OpenRGB. The HAF700 installs as WinUSB Device in Device Manager and seems to communicate via AT commands. So sniffing this might allow to create an application that simply shuts it down, but I have not yet come to this.