Haswell-E + X99 Motherboard Temporary Guide - OS X 10.9.4
Bit of an oddity, probably something dumb on my end. Rather than doing a fresh install of OS X, I moved my DIY fusion drive over into my new X99 machine. Copied mach_kernel over onto the Fusion Drive root, and rebooted. I selected "Fusion Drive 1" and ended up with the error "Can't find /mach_kernel" - so I said, "That's weird, I must not have copied it."
Entered boot flags again and selected the Unibeast drive, and suddenly, I'm in my Fusion Drive? Ran Multibeast as normal, rebooted, and my BIOS doesn't seem to think the Fusion Drive is bootable. Even after Multibeast is run and Chimera installed, booting into the Unibeast drive and selecting the Unibeast drive to boot from yields a boot into my Fusion Drive. What the heck?