bootcamp won't let me install windows using GPT OR MBR partition style

I've been trying for days to get windows 7 onto my "new" 2009 mac pro. it's fully decked out and i hope to install windows 10 onto it after installing 7. I've tried windows 7, 8 and 10, getting different error messages every time at the same spot. When selecting the partition I want to install windows on, I get error messages and am unable to proceed hitting the next button. I've tried everything i can think of, from partitioning under ntfs through to ex-fat on the main SSD (which gives me a whole other error), to removing the other SSHD's and installing whilst ignoring bootcamp entirely. I've finally got a solid error message installing windows 7 that reads "Windows cannot be installed onto this disk. The selected disk is of the GPT partition style."

Here's where it gets frustrating (AGAIN)... when I make the disk MBR by formatting it as ex-fat or vice versa, it simply switches to say cannot install onto a disk of the MBR partition type. I'm absolutely lost. I've looked through countless forums and feel like i've tried everything. It's a 2009 mac pro, and i'm using the superdrive to install windows. please help as this is driving me crazy!

If you're following the Boot Camp instructions, you should have no problem. Boot Camp first partitions your selected drive to make room for the Windows installation, and then it formats that partition to FAT-32. From there, it guides you to install Windows. The Windows installation will ask where it is to be installed and then the FAT-32 partition that was created must be formatted to NTFS before the Windows 7 installation will proceed. Don't know what you're doing wrong?

What kind of disk are you trying to install Windows on? Is it your primary boot disk where you have macOS installed? You can not install Windows to a second hard drive or external hard drive without hacks.

chscag said:

If you're following the Boot Camp instructions, you should have no problem. Boot Camp first partitions your selected drive to make room for the Windows installation, and then it formats that partition to FAT-32. From there, it guides you to install Windows. The Windows installation will ask where it is to be installed and then the FAT-32 partition that was created must be formatted to NTFS before the Windows 7 installation will proceed. Don't know what you're doing wrong?

What kind of disk are you trying to install Windows on? Is it your primary boot disk where you have macOS installed? You can not install Windows to a second hard drive or external hard drive without hacks.

Click to expand...

I've tried installing it on my primary drive, however bootcamp doesn't allow me to select it so i do that manually. I have also tried on one of my sshd's, which seems to have worked for loads of other people? I'm not sure what you mean by hacks... It simply doesn't work any way I try to do it.

I should also mention that if i remove all other hard drives apart from my ssd in which sierra is installed, I get an error that reads "You cannot partition an external disk, a RAID disk or an internal disk on which FileVault encryption is in progress".