If you are trying to initiate a new disk or format your computer and when you prepare a USB drive to format your computer you will come up one or another of these options. You have to chose one. You cannot just go either one of them. An MBR boot disk must work with the Legacy (BIOS) boot mode and to work with UEFI, the disk should be in the GPT partition style. Here I will explain how you can decide for your machine.

Legacy or UEFI?

BIOS (now it is also named Legacy) was long used as only operating system for your motherboard. You may remember a little while after pressing the power button on  your machine before windows loads, on the dark screen there for little around a second you will see a text : Press Delete / F12 / F2  etc… button for setup. The setup here means the menu of the BIOS the operating system of your motherboard. It is usually a blue screen with gray menus.

Overtime, BIOS has evolved and allowed manufacturers to modify and it to fit their needs and their brand’s tastes. A UEFI bios setup is now mostly like a retro website. We can even use a mouse to navigate where on a “Legacy Bios” we are only allowed to use our keyboards.

So, wich one is yours? Follow this step by step navigation on your PC to find out.

To enter BIOS, do not miss the messages on startup.
Legacy BIOS Mode

How to find your BIOS mode?

  1. Right mouse click on windows “Start”
  2. Click on “Run”
  3. Enter “msinfo32” in your run console
  4. Find info “Bios mode” in the window
Run "msinfo32" for sytem information


Your disk is either initiated as MBR or GPT. GPT is the new standard. It is first introduced as part of the UEFI initiative. It’s more flexible and has better compatibility with modern hardwares.

How to find your HDD/SSD mode?

  1. Right click on “This PC” computer icon.
  2. Select “Manage”
  3. Click on “Disk Management” under “Storage”
  4. Find your HDD/SSD disk drive
  5. Right click and select “Properties”.
  6. Select the “Volumes” in the top menu and find your “Disk Partition Style”
Click on "Manage" on your PC
Right click on Disk and click on "Properties"
Find "Partition style"



  •  By IBM
  • 4 Primary Partitions
  • 2.2TB Max Partition Size
  • Actual Location is on first sector only.
  • No Data redundancy
  • No error dedection/correction


  • By Intel
  • 128 Primary Partitions
  • 8.6 billion tebibytes Max Partition Size
  • Actual Location is on first and last sectors
  • Data Redundancy support
  • Error dedection/correction support

How to Convert From MBR to GPT?

  1. Back up or move the data on the basic MBR disk you want to convert into a GPT disk.

  2. If the disk contains any partitions or volumes, right-click each and then click Delete Partition or Delete Volume.

  3. Right-click the MBR disk that you want to change into a GPT disk, and then click Convert to GPT Disk.

Aix Observer
Aix Observer
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