Hi, the title doesn't mention all the problems I had, because my hope is to solve them and give an example of what's needed if somebody else wants to try that too... First of all, I read like 20 different guides, mixed up but not got to a happy ending yet (my fault probably ), I have the links if necessary. Before Mavericks I had a BootCamp dual boot configuration with Lion and Seven x64. That was fine but, because I replaced the hard drive with a SSD model, I took a chance to set as the newest environment as possible. I found out to my sadness that Mac Mini 2010 (model 4,1) is not supported by BootCamp 5 therefore Windows 8/8.1 neither. But there are workarounds to install BC5 and the other missing (mostly graphic) updated drivers. The problem is to get to that point. A second aspect is that, even if I have a DVD unit (by the way I own an external one too), don't ask me why, it doesn't read Windows DVD properly, so I decided to go for a pen drive installation, that is possible with another workaround. So, goals: 1) Install native OSX Mavericks + Windows 8.1 x64 2) Complete the Windows installation through a pen drive, not using DVDs What I did: 1) Modify Info.plist file as it follows: 1.add my Bootrom Version at the top in the "DARequiredROMVersions" section 2.Delete "pre" from "PreUSBBootSupportedModels" that becomes "USBBootSupportedModels" and add my Model Identifier at Top First. 3.Delete my model "Mac mini 4,1" from the Win70onlymodel Editing has been done with TextEdit plus XCode4 and thanks to this post. Cool, now BootCamp assistant in Mavericks has more features enabled, like the possibility of setting a flash drive up to install Windows or prepare a boot device with Windows 8, not only 7. Because I read that there are some problems to make the hardware being immediately recognized, I decided to postpone that part and not including Bootcamp drivers in the device. The pen drive was set up on a MacBook Retina 2013. After creating a partition (through the assistant), here come the problems. Windows 8.1 installation starts, I'm asked to choose a destination partition but whatever I do, a message appears and says: "windows cannot be installed to this disk. The selected disk has an MBR partition table. On EFI systems, Windows can only be installed to GPT disks" I tried to - re-format the disk (I don't see any advanced options by the way, like this) - install rEFIt - use Windows 7 Tools, but it keeps telling that "unit is in use" and I can't reverse the .iso on the pen drive - change the partition table of the pen drive, from MBR to GPT but then I cannot copy the contents of .iso inside then I don't wanna make an upgrade from Seven and as far as I know Win8 use EFI just like OSX does, so what d'u suggest me to do? Are there any other ways I haven't explored yet or the solution is to re-format the disk again with the GPT file structure, install OSX and then Win8.1 I can provide some images or details in addition. Thx a lot for ur help guys.