@CitizenJoe
I wish I could say for sure what the video flow in your system is. Unfortunately it seems that this is one aspect of Windows machines that is upto the manufacturer, and isn't very standardized.
When you look at 'Setup multiple displays' in the nVidia control panel, are your displays shown under your nVidia gpu?
In my case, my Laptop Screen is NOT listed in the 'Setup multiple displays' section of the control panel (it is only configurable via the Intel video control panel).
I do find it a little strange that your external connections are shown as part of the Intel HD card.
Mine are shown within the nVidia card/block (in the PhysX section).
My testing hasn't shown any difference in performance between running Isadora on my internal Laptop Display or a External Display (Intel managed display VS nVidia managed display) assuming Isadora is setup to use the Dedicated GPU (otherwise things are unstable).
It seems that some video transfer is synced between the 2 gpus at all times.
@Fred , some work is being done in profiling and optimizing gpu usage on Windows.. so I am hopeful we will be seeing some improvements in the 'near' future :)