I'm using currently Synapse version 1.67.9. This version works with Sierra 10.12.3 (and at least 10.12.2.).
With version 1.68 the system does not boot. I reported this to Razer immediately after the release of 10.12.3 but they have not replied so far.
BTW kext-dev-mode=1 does not have any...
Same here. I noticed that I could overclock more with 2202.
To roll back you need to save 2202 bios on usb stick and use the bios flash button in the back panel. For instructions see --> https://www.tonymacx86.com/threads/storks-gene-build-asus-maximus-viii-gene-i5-6600k-gigabyte-gtx-950.181272/
Just updated my Asus Maximus VIII Ranger bios from 2202 to 3007 . After this update nVidia web drivers do not load anymore.
Before update it worked fine. My GPU is Asus Strix GTX960. Using Sierra 10.12.2.
I uninstalled the driver and reinstalled it (WebDriver-3188.8.131.52f02.pkg) but no help...
If you want to have Windows as your primary operating system then just define UEFI to use that SSD for 1st boot.
You will need Clover to boot OSX on that specific SSD. If you want to boot OSX just use the F8 to select that drive.
In addition if you want to you can hide Windows SSD from Clover...
You say that the system boots ok but freezes after login. It could be a broken control panel item for Firestudio.
Try this --> http://www.wikihow.com/Remove-an-Item-from-System-Preferences-on-a-Mac and see what happens.
Then reinstall Firestudio software.
Remove firewire card and see if you can boot normally (though use -f first time booting as you might need to build cache).
Do you have a possibility to try another firewire card? Firewire cable?
If you boot with -v do you get any error messages?
Since you can boot with -f flag (which rebuilds kernel cache) I believe it is somehow connected with drivers i.e. kexts.
The conflicting driver could be the one for Firestudio. Have you done any updates recently? Firewire card broken?
PS. Holding shift key during boot has no effect in...