I have a new WD 6TB drive, I boot from Windows10 USB, It originally partitioned the drive as MBR, Windows installed, however I could only use 2TB of the 6TB drive and it would not let me create more 2TB partitions. I then Googled the problem and people are saying the partition it as GPT. I then used diskpart and converted to GPT. However, now when I attempt to install Windows I get an error unable to install to GPT formatted drive. I can't find UEFI in my BIOS, did they have it in 2014? I have Asus M5A78L-M USB3, I already checked and I already have the newest version.
I then used diskpart and converted to GPT.
You cannot install Windows in this way. If properly booted into the Windows installation environment, with UEFI mode enabled, Windows will automatically use GPT. It actually is the only partition type that Windows can be used with UEFI mode enabled.
It originally partitioned the drive as MBR
If Windows partitioned the drive as MBR, it means you booted to the installation environment, while in Legacy Mode and the only valid partition type that is supported while in that mode is MBR.
However, now when I attempt to install Windows I get an error unable to install to GPT formatted drive.
You still have Legacy Mode enabled, which means Windows is unable to install to a GPT partition disk, the only partition type Windows supports while in Legacy Mode is MBR.
I can't find UEFI in my BIOS, did they have it in 2014?
If there is no method to disabled Legacy Mode which is sometimes called, Compatibility Support Module, then your system does not support UEFI and thus you cannot install Windows to a GPT partitioned disk.