My 2014 Retina iMac doesn't like most things. One of it's downfall's is that if you have anything remotely usefull attached to it, it won't work. I got the iMac so that i could use it for the OSx side of things but still have the ability to reboot into Windows to play some games. But, if I have my (original) microsoft xbox360 wireless gamepad receiver hooked up, you can't boot the iMac. But if I have any thunderbolt drive hooked up to the iMac, then mt Win7 bootcamp will stall after the psudo bios screen fashes up and you are stuck to get it to load. But if you have a USB hard drive plugged in, you have a 50% chance that it will just reboot itself and you have to try again holding down your option key to select Windows. I have Win7 right now installed as bootcamp. There is not enough free drive space or something else wrong that won't let me upgrade the install to Win10. Bootcamp assistant won't let me delete the bootcamp install, so I can't even try to load Win10 on the internal SSD. I did get somehow a copy of Win10 installed on a 500gb harddrive via USB3 that will work but it's noisy as heck and I know the drive is about to die. I have never managed to get it work off a new SSD. I have a Thunderbolt drive that I have but can't figure out how to get Windows 10 to load onto it. I don't know if I have to figure out how to delete the current bootcamp and get the partition back to being a single drive and try again to get bootcamp to work. Has anyone managed to get Windows 10 loaded onto a thunderbolt SSD drive? If so what are the instructions?