If you have installed Windows 10 for a long time, for example in a VM or directly on your PC, the old BIOS/MBR boot mode may still be in operation. With the more modern UEFI mode including GPT partition table, your PC may start much faster. In addition, the modern UEFI has some other advantages, such as higher security. And last but not least, the UEFI mode is mandatory if you want to update your Windows 10 to Windows 11. Fortunately, switching from MBR to GPT is possible under Windows 10 without reformatting using on-board tools.
UEFI - what is it?
UEFI, the "Unified Extensible Firmware Interface", the old one has been said for some time BIOS substitute. Of the Disadvantage of the BIOS is that it is a hardware chip, which means that it has certain limitations. And updates aren't easy either. It therefore makes sense to do without this "achievement" that is more than 40 years old.
Check if UEFI or BIOS is active
(U)EFI has been used by Apple since the Intel switch, the implementation under Windows was bumpy for a long time, which means that a whole range of Windows PCs are likely to be on the road that still use the BIOS mode with MBR partition table. The benefit of UEFI with its GPT partition table? Significantly higher speed, better security and easier expandability, in short: everything that PC users need.
And then UEFI is also for the Windows 11 update mandatory requirement. You can check the mode by calling up the system information (msinfo32.exe) under Windows: Under "System Overview" you will see either the entry "UEFI" or "BIOS" next to "Bios Mode". If it says BIOS, you should become active and switch to UEFI – that also works, by the way virtual machines in Parallels or other virtualization solutions!
Optional: Create local administrator
First, when using a live account on Windows, you should make sure you have a local user with admin privileges on hand. Because the login with the live account does not work (at least in our tests). To do this, go to the settings and select “Accounts”.
Click on "Family & other users" and create a local user account with the plus symbol "Add someone else to this PC". You then have to give them administrator rights by clicking on "Change account type" and selecting "Administrator". After confirming with "OK" you have to log in to Windows with this new user.
Start system restore with command prompt
First, make sure that you have backed up all important data on your Windows computer! Then open the "Update & Security" item in the system settings. Click on "Recovery" and then under "Advanced startup" on "Restart now". The computer will now restart with advanced Windows recovery.
In the recovery interface, select the "Troubleshoot" option and then select "Advanced Options" and "Command Prompt".
It will take a while for the next window to appear, but that's OK. Windows will then show you a list of existing users. Select the local administrator and enter the password to start the Windows command prompt.
Convert MBR to GPT and thus BIOS to UEFI
Then only two simple entries are necessary: You must first check whether your PC is suitable for converting from MBR to GPT and thus from BIOS to UEFI. Therefore, type in the command prompt first
a. If no error message appears, you can convert your MBR to GPT - and thus use UEFI - with a simple
start. The conversion doesn't take too long. You can then close the command prompt and select "Turn off PC".
Turn the PC back on and be happy
Now switch your PC back on: You will probably notice that it starts up much more "smoothly" and faster. In addition, it is now ready for future updates. You can now conveniently check whether everything worked: call msinfo32.exe again and see whether "UEFI" is now under "BIOS mode". You can also take a look at the Disk Management by running diskmgmt.msc: If you click on the Windows disk here at the bottom left and select "Properties", you can see in the "Volumes" tab that your Windows is now working with the GUID partition table (GPT).