After lots of experimentation, it turned out that the best boot parameter so far (Ubuntu 16.10 alpha July 2016) is:
Otherwise (e.g. with acpi=noirq), there is a crash trying to load the nvidia card and an issue with ACPI trying to load _DSM. If you want to disable the nivida card completely, for 6W or more of power savings, use nouveau.modeset=0. This might need to be in addition to pci=noacpi.
This might work for lots of other notebooks, especially with Nvidia graphics and a Skylake CPU, e.g. the MSI GE62 6QF series.