Hello everyone, that is my guide to successfully install OS X Yosemite for the Gigabyte GA-Z97X-UD3H. It works everything except iMessage and FaceTime, you can enable them following this guide
http://www.tonymacx86.com/general-help/110471-how-fix-imessage.html
First of all, remove all the RAM sticks except one.
Follow this guide
http://www.tonymacx86.com/445-unibeast-install-os-x-yosemite-any-supported-intel-based-pc.html from step 1 to step 4.
IMPORTANT: when you will boot for the 1st time and when you just installed Yosemite (before installing drivers with MultiBeast) boot with these flags: "-x GraphicsEnabler=No"
Install MultiBeast with these options:
Quick Start > DSDT Free
Drivers > Audio > Realtek ALCxxx > ALC1150 (because that's the audio card we have in our motherboard)
Drivers > Disk > 3rd Party SATA
Drivers > Misc > FakeSMC v6.11.1328
Drivers > Network > Intel > AppleIntelE1000e v3.1.0 (to enable the ethernet connection correctly)
Drivers > AppleRTC Patch for CMOS Reset
Bootloaders > Chimera v4.0.0
Customize > Boot Options > 1080p Display Mode (of course just if you have a 1080p display)
Customize > Boot Options > Basic Boot Options
Customize > Boot Options > Hibernate Mode - Desktop
Customize > Boot Options > IGPEnabler=No
Customize > Boot Options > Kext Dev Mode
Customize > Boot Options > Use KernelCache
Customize > System Definitions > Mac Pro > Mac Pro 3,1 (usually it's better choose this to avoid kernel panic)
Customize > Themes > tonymacx86 Black (you can choose the one you want)
Then, just in case you have an SSD, check this option:
Drivers > Disk > TRIM Enabler > 10.10.0 TRIM Patch
Now cross your fingers and reboot! Press F12 when the PC is restarting and boot from the drive you installed Yosemite, everything should work fine! I'll post the guide to enable HDMI audio ASAP. Hope this will help!
EDIT: just in case you have a kernel panic, boot up with -x in safe mode and install this MultiBeast driver:
Drivers > Misc > NullCPUPowerManagement