A:Answer The Q528 uses Intel Iris by default. The NVIDIA GPU is used (automatically) only if you're gaming - if the Iris is at 100%, or even disabled, the NVIDIA will not be used unless you're gaming (which I found strange). The Intel or the Iris GPU can be disabled/enabled from Device Manager, no need to reboot.
I'm not a gamer, but use multiple (4K) displays with lots of video streaming - I found the Intel Iris working great