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This is related to a previous question: Why is the "Extend Partition" option disabled?

I'm trying to understand how all pieces of BIOS, OS and disk configuration to determine if I need to update my BIOS to support UEFI so that I can access all the space on a 4TB drive.

My current set up is:

  • Asus M5A88-M motherboard w/ BIOS version 0601
  • Windows 7 Home OS w/ MBR disk type

I understand I would need to update my BIOS to 1702 for it to support UEFI which is needed for me to format my disk as GPT instead (I think I've got that right, but feel free to correct me if I'm wrong).

However, if I upgraded to Windows 10, would I still need to update my BIOS to enable GPT support?

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No. The BIOS just loads the bootloader in the first sector and doesn't care about whatever format the drive is1. Therefore technically you just need a bootloader that supports GPT in order to boot from a GPT drive in BIOS. You don't need to update the BIOS (in fact updating the BIOS does nothing to address the GPT problem). However Windows bootloader doesn't have this capability so you must boot from a MBR drive if you're using BIOS/legacy mode

If your mainboard uses UEFI then it already supports booting from a GPT drive. So you don't need to update the UEFI firmware either

Note that in general you can't update the BIOS to get UEFI, since the UEFI firmware is a lot more complex and bigger than BIOS and won't fit in the BIOS chip. You can install a software UEFI though

Since your M5A88-M doesn't have UEFI support, you can only install Windows on a MBR disk. If you want more space you can install additional GPT disks for data and leave the MBR disk as-is. If you must install Windows on a GPT disk without a MBR HDD then you have several options

  • Use an external MBR flash drive for storing Windows boot files
  • Install a software UEFI implementation like rEFInd or DUET, but this is no easy task for non-techies, and boot up time will be slower
  • Install Linux on GPT and run Windows inside a virtual machine if you also need Linux

For more information read


1Although there are buggy BIOSes that eagerly check the MBR signature or the active boot flag and refuse to boot on such drives

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