Thought I would give back to the collective pool of knowledge and share this with everyone. I was able to get Yosemite installed on my X9DAi system using UniBeast and MultiBeast. It took some trial and error to get the right MultiBeast settings worked out, but so far, everything has worked very well (no Audio). System Specs: ---------------- * MB: SuperMicro X9DAi 2-socket motherboard (BIOS vers: "R 3.0a") * CPU: E5-2630v2 CPU (one installed today, the second will get installed next week) * RAM: 64G (4x16G) DDR3-1600 RAM * Power Supply: 650W PS * Video: ATI Radeon HD3870 512M (Yosemite reports it as an HD 3650) * Unibeast: v5.0.1 * MultiBeast: MultiBeast - Yosemite 7.0.1 The installation went very well as I followed the great instructions here: http://www.tonymacx86.com/445-unibeast-install-os-x-yosemite-any-supported-intel-based-pc.html. I had to add the boot options "npci=0x2000 GraphicsEnabler=Yes" to get the install working properly. The only issue I had was getting the video driver sorted out after installation (during install I was getting 1900x1200 on both displays, but after install I was getting 1024x768). After installing Yosemite, I ran MultiBeast and used the following settings: --------------------------- Quick Start > EasyBeast Drivers > Disk > Intel Generic AHCI SATA Drivers > Misc > ElliottForceLegacyRTC Drivers > Misc > EvOreboot Drivers > Misc > FakeSMC v6.11.1328 Drivers > Misc > FakeSMC v6.11.1328 Plugins Drivers > Misc > FakeSMC v6.11.1328 HWMonitor Application Drivers > Misc > NullCPUPowerManagement Drivers > Network > Intel > AppleIGB v184.108.40.206 Bootloaders > Chimera v4.0.0 Customize > Boot Options > Basic Boot Options Customize > Boot Options > Generate CPU States Customize > Boot Options > GraphicsEnabler=Yes Customize > Boot Options > IGPEnabler=No Customize > Boot Options > Kext Dev Mode Customize > Boot Options > Use KernelCache Customize > System Definitions > Mac Pro > Mac Pro 6,1 Customize > Themes > tonymacx86 remixed Finally, I had to edit the /Extras/org.chameleon.Boot.plist file and add "npci=0x2000" to the Kernel Flags line. Once the system rebooted, I was greeted by a dual-screen HD display! The system has been up for a few hours, and appears to be working great. I ran the CPUs at 100% while also running memtest in a terminal window for +10mins. No issues whatsoever. I also ran some network and SSD speed tests - everything passed with flying colors! Video problem --------------- As outlined in this post (http://www.tonymacx86.com/desktop-c...-hd-3870-white-screen-after-installation.html) I was able to get 1900x1200 resolution during Yosemite installation but only got 1024x768 after installation. The fix was to move the AMDRadeonX3000 kernel drivers from the /System/Library/Extensions folder to a backup folder and reboot. Thanks to everyone who is involved with the UniBeast and MultiBeast projects. Without their work, I could have never built my new system!