Just a minor update on anyone trying to update their system to 10.12.6, please be aware that it may be a slightly more complicated process to upgrade. I had my system (GA-Z170N-WIFI) working with the 10.12.6 combo update, but less than a week later it stopped booting up. Not sure if it was due to a faulty Intel P600 NVMe drive, but installing 10.12.6 on two separate drives, one using the combo update and one using Unibeast installer stick gave me the same bootup problems, which I finally solved using the methods below.
1) Booting 10.12.6 from Unibeast USB stick
If you are using a Unibeast USB, I suggest using the latest 7.11 Unibeast for the Sierra 10.12.6 download. Also place the latest Lilu.kext, IntelGraphicsFixup.kext and NvidiaGraphicsFixup.kext into EFI/Clover on the USB. The stick should boot without any extra options.
2) Updating existing system with Combo
If you are upgrading from 10.12.5 after using the 10.12.6 Combo update, your system may not boot up properly afterwards for you to complete the Nvidia 10.12.6 driver update (WebDriver-378.05.05.25f01.pkg) to get the system working normally, plus the updated RehabMan's 10.12.6 NVMe driver in the NVME/EFI/Clover folder. To get around this issue, you will need to boot using the updated Unibeast USB stick described above, and at boot up, press F12 to select your Unibeast USB stick's Clover boot partition and boot from that or preferably a 2nd test harddrive to allow you to copy whatever files to your NVMe. Then, at Clover menu, select your test harddrive and using the Clover options, select nv_disable=1, nvda_drv=1 and debug=0x100. This should allow you using the Intel driver to boot right into the new system via the Nvidia HDMI port. From there you can install the latest Nvidia web drivers and add the updated Rehabman NVMe 10_12_6.kext to your test drive or NVME's EFI/Clover folder. Also add in there, using Kext Utility the updated Lilu.kext, IntelGraphicsFixup.kext and NvidiaGraphicsFixup.kext, the Rehabman NVMe Hackr kext, FakeSMC and the USBInjectAll from the EFI/Clover/kexts/Other folder. Then change using Clover Configurator, the config.plist for the test/NVMe drive to boot with darkwake=0, dart=0, debug=0x100 and nvda_drv=1. Also make sure your SMBIOS settings are correct ie. iMac 17,1 definition with valid serial number & SmUUID, and that the Inject NVidia setting has been checked in Graphics. Then in terminal run sudo touch /System/Library/Extensions && sudo kextcache -u / and reboot.
If this fails to boot, run Kext Wizard's system and cache rebuild on the affected drive via another machine or spare boot drive. In the case of the NVMe, use another drive to boot in to perform the cache rebuild.