I have had UEFI on my system for a long time under Windows 10. Microsoft made change to force Secure Boot on Windows 10 that my computer has no support for. Now I can no longer use UEFI with Windows 10, because my computer will not boot successfully. I cannot disable Secure Boot in my BIOS, and Microsoft make a call via Secure Boot that crashes my computer immediately at startup. Microsoft will not fix this, so I just installed Windows 10 with a BIOS MBR boot instead. I know there is a limit of 2TB as the maximum disk size, and my C: drive has a partition set as this size. My total disk space is 5.46TB. What must I do to create additional partitions? Right now I have 3.46TB of unused space. The Windows 10 setup would not allow me to create additional partitions (I do not remember it being this difficult with older versions of Windows). I cannot extend or create secondary partitions at all.

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