hi folks im about to go crazy. i tried installing win 8.1 on my 2013 imac (3tb fusiondrive) as i did it on all my mac systems. in windows setup (after setting the partition, creating usb starvolume etc.) i get the error "Cant install on this Partition - no GPT-Partition". i formated it again (with win installation tool)... no success. back in osx i wanted to start again and delete the partition... but bootcamp assistant hasn't found my bootcamp partition... i cant restore my complete 3tb fusiondrive to start over again. i cant combine both drives with the osx diskmanager. i cant change the partition layout. now i formatted the partition as a mac os journaled in hope that i can combine it then... no success. i cant format the partition as an ntfs too to start a clean windows installation! what is this?? my exBootcamp partition appears not as a partition of my Macintosh HD. it looks like an independend drive in the diskmanager but in the PArtition Layout of my Macintosh HD the ohne Partition is maked as part of the fusiondrive. weird. excuse my english... but im really in trouble. i really need your help? i thought all the 3TB Bootcamp probs were solved???!!