I finally managed to move from 10.8 to 10.10 on my MP09. On my previous attempt I had some strange slowdowns that made me roll back to Mountain Lion. There's one problem that needs fixing. On 10.8 I had a configuration that allowed me to boot to Win8 without using Bootcamp or the boot screen. Here's how it worked.... OSX was on a 3 X Intel x-25 Raid0 array Win8 was on an external SSD that was connected to an eSata port on an Accelsior_E2 I configured OSX so that the Windows SSD was the default boot drive. I would then toggle the OS that I wanted to boot from the powers switch of the external SSD enclosure (if the SSD's power was off the MP would boot to OSX) After installing Yosemite the setup won't work. When I choose Win8 as the boot drive (from OSX) the boot fails with a black screen with an error message "No bootable device -- insert boot disk and press any key" If I choose the boot drive manually (by pressing down option key) I can boot normally to Win8 Hardware-wise the difference to the old setup is that my OSX is now installed on the Accelsior Any idea what's the source of the problem and how to fix it? I'm planning to get a GTX980 or a Titan X and at that point I won't have access to the boot screen.