I have followed these steps to install windows 7 home premium x64 on a 3tb drive (asus z87-z motherboard):

Windows Setup: Installing using the MBR (Master boot record) or GPT (GUID Partition Table) partition style

In the console window, diskpart, I ran:

select disk <disk number>
convert gpt

Then when using the GUI to partition the disk to install windows, it always reverts back to MBR (list disk shows no asterisk under gpt).

I tried again, in this case cleaning and converting the disk, then pointing windows at the partitioned disk and letting it install.

By going to Control Panel-Administrative tools-Computer Managment-Storage-Disk Managementand checking the properties of the disk I can see that it is now a MBR.

Is there something I have missed? Could there be something in my setup incompatible with GPT that is causing this?

  • May be that I'm not installing windows in UEFI mode? Is that a boot option? Nov 15, 2014 at 11:12
  • That is the first thing that comes to mind given all the information you provided. it Compatability boots after the intital load up of the disk ? Because the bios/uefi was set to legasy boot first or something? In the boot and CSS sections.
    – Psycogeek
    Nov 15, 2014 at 11:15
  • Right. I solved my problem: I made sure I was booting from dvd in uefi. I disabled fast boot and set secure boot to "other OS" (ie off) [Can't comment on whether this was required, sorry]. I then did the cleaning and convert again. Windows Still gave the warning that it couldn't install and manual partitioning resulted in 2.2tb max partitions. So it didn't do it manually, I just pointed at the cleaned and converted disk and let it install. Checked, and it seemd to have worked. Nov 15, 2014 at 12:06
  • I found this related question: superuser.com/questions/616340/… Which is what gave me the idea to turn off secure and fast boot. Nov 15, 2014 at 12:07

1 Answer 1


When your computer turns on, press the appropriate F# key on to enter your system's BIOS/EFI. In there look for a mode setting that allows you to choose between booting in CSM (Legacy), or EFI, choose EFI mode.

Save your changes, exit the BIOS/EFI, and boot up the Windows installation disc. You should now be able to format the disk as GPT, and install to it.

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