I am trying to install Windows 8.1 on a secondary drive. What I have done is taken out my OSX drive and replaced with the secondary drive. I have booted OSX from a backup on a USB3 hard drive. When I boot into the backup and startup Bootcamp to go through the process it has the Windows installation part greyed out. Is there a reason for this and what are the solutions? I have tried to partition the OSX drive and have never succeeded in installing Windows. OSX seems to change the installation to MBR and of course it can't recognise. I hav tried the workarounds to no avail. Besides I want two drives and I know Windows will not install if you place it in the Caddy in the Optical Drive Bay.