Hey, Quick: I'm getting kernel panics whenever I try to boot into OS X Mavericks with a non-EFI GPU in a PCI slot. Long: My GF has an 8-core Mac Pro 3,1 w/ 8 GB of RAM and both a Radeon 2600 XT and a Sapphire Radeon 7950 (non-mac edition!). Under mountain lion, the GPU upgrade was plug-and-play, no boot screen of coure, of but it worked just fine once the OS loaded drivers and such. I removed the 7950 to upgrade to mavericks, upgraded, booted into OSX, did a back-up, then I shut it down, added the 7950 (w/ appropriate power cables of course) and now I get kernel panics at boot. Verbose boot mode makes it to something like: before it reboots and displays the kernel panic screen. Has anyone run into this problem before with an inkling as to how I might fix it?