I've got an Asus P8Z77 motherboard with a core i7 3770 processor, and a Geforce 660 video card. I'm running Windows 8.
While I primarily use the latter, there's situations where I want to use the HD4000 video adaptor built into the core processor - for example where I want to take advantage of quicksync. How would I do this?
Apparently the iGPU Multi-Monitor setting under advanced/system agent configuration/graphics configuration needs to be turned on. This is labelled for being for virtu but is necessary for the integrated GPU to be detectable by windows, even if you arn't running virtu. This setting is still around on more modern intel systems - with my z390 and 9th generation intel processor its still an available option, and it worked exactly the same on my old box through windows 8-10
On my Asus Z77 board the option looked something like this
Obviously the location of this may vary with different motherboard brands and the name of the setting may be different.
My guess is since lucid logix uses both GPUs, it tells the motherboard to simply run both - independent of whether you're running more than one monitor (with lucid outputting what you're rendering on the dedicated GPU to the integrated GPU), or using a multi-monitor set up taking advantage of both the IGPU and Dedicated GPU as independant outputs without lucid.
In my case this let me use my onboard video for a theoretical 3 additional outputs, rather than the switching that lucid does, and use quicksync alongside my discrete card.