just a long shot but could it be something to do with the "headless" implementation in smOS?
What do you mean "headless" implementation? As far as I can tell the headless issues are due to the motherboard bios and have nothing to do with the OS?
most OS need a active video line into the gpu to signal it has something plugged in or OS doesnt "use" it to say
like windows if you run a dummy plug in it. its ten times easier to get 5-7 gpus running without to many issues
linux you can setup a script that will "trick" the OS into thinking it has an active video line into the gpu hence "headless"
smOS is a headless linux OS
An active video line helps the OS see it has another means of video other than the on board video from the cpu or motherboard
little side note.. headless also includes keyboard and mouse not just the monitor