On my new iMac /w a 1TB Fusion Drive, I tried to install Windows 8 (still technically unsupported) using the following method:
Everything was proceeding just fine; I had Boot Camp copy all of the Windows 8 files (a legitimate, store-bought copy) to a bootable USB drive - a feature only available on new Macs running Boot Camp Assistant that don't come with an internal optical drive - and create a 102 Gb partition on the Fusion Drive. It then rebooted and was proceeding through the Windows 8 setup wizard as should be expected, but it couldn't modify any of the partitions on the Fusion Drive and wouldn't proceed. I accepted defeat and decided I would just wait until Windows 8 is officially supported before trying again.
Now, every time I turn the computer on, I get an error message saying "No Bootable Device...", unless I hold down the Option key and manually select "Macintosh HD" (the only boot device listed). I already removed the primary Windows 8 partition, but it hasn't fixed the issue.
I'm thinking that it's one of the 'hidden' partitions causing it to behave like this, or something wrong with the EFI bootloader, but I don't know how to proceed. Any thoughts on this?