Comprehensive Guide: Switching your BIOS from Legacy to UEFI in Windows 10

Making the change from legacy BIOS to UEFI firmware seems intimidating, but I‘m here to walk you through the full process step-by-step. With this in-depth guide, you’ll understand all the technical background, prepare your system properly, navigate tricky configuration changes, and have all the troubleshooting advice needed to switch modes safely.

Converting to UEFI delivers noticeable improvements in system performance, security, and functionality. It also paves the upgrade path for moving to Windows 11 down the road. While it does take some care to switch properly, I’ll be with you every step of the way until you’re running smoothly on modern UEFI firmware.

We’ll start by understanding what BIOS and UEFI are, then outline why upgrading makes sense. Next I’ll provide the full practical walkthrough to transition your PC properly. And no worries – I have you covered if any issues pop up along the way! Let‘s get into it…

What is Legacy BIOS and What is UEFI?

First, a quick history lesson so you understand your PC‘s underlying firmware…

The legacy BIOS (Basic Input/Output System) has been running under the hood facilitating hardware interaction and bootstrapping operating system launches since the dawn of the PC era in 1975. Every time you press the power button on an older computer, legacy BIOS firmware initializes components, performs a power-on self-test, then loads the OS bootloader.

This 40+ year old standard did the job well for a long time. But it has some limitations including slower boot ups, a text-based interface, the 2.1TB partition size limit, and lack of modern security capabilities.

UEFI (Unified Extensible Firmware Interface) emerged in 2005 as a long-term replacement for BIOS to overcome such constraints. It delivers:

  • Faster boot experience – 3x quicker startup is common
  • Support for modern large capacity drives beyond 2.1TB
  • Enhanced security features like Secure Boot
  • Improved graphical interface to navigate firmware settings

Rather than an aging 16-bit design, UEFI uses flexible modular 32 and 64-bit architecture. This facilitates integration of more sophisticated features going forward. The chart below illustrates some of the major differences in technical capabilities:

With support for the newer GPT partition scheme and advanced configuration options, UEFI delivers a modernized pre-boot experience before handing off to the OS.

Upgrading is easy enough these days, so with Windows 11 on the horizon many PC owners have good reason to make the switch from legacy BIOS to UEFI…

Why Migrate to UEFI Firmware?

There are a few motivations for transitioning to UEFI:

  • Faster boot – UEFI devices see over 30% quicker startup times versus legacy BIOS systems according to
  • Better Performance – The firmware can initialize hardware and hand off to the OS more efficiently. For example, one analysis found 7% faster game load times after upgrading (MaximumPC).
  • Enhanced Security – Features like Secure Boot prevent potentially malicious unsigned code from persisting through reboot.
  • Modern Touch Support – The graphical interface works well with newer tablets and 2-in-1 devices.
  • Future Proofing – UEFI will be the standard for all devices going forward so adopting early eases future upgrades. For example, most systems require UEFI to upgrade to Windows 11.

With industry momentum clearly shifted to UEFI as the new firmware standard moving forward, upgrading clears the path for maintaining a modern, optimal Windows experience…

Step-by-Step Guide: Safely Transitioning to UEFI

Next I’ll outline the full procedure to securely switch your boot firmware from legacy BIOS to UEFI in Windows 10:

1. Confirm Your Starting Point

Let‘s begin by validating whether your PC currently runs on legacy BIOS or UEFI firmware.

To check, open the System Information app (search the Start Menu or run "msinfo32.exe"). Under the System Summary, BIOS Mode will show what firmware your device boots with:

If "Legacy" is listed, you are not yet running UEFI.

We can also confirm the partition scheme used on your hard drive:

  • Legacy BIOS uses Master Boot Record (MBR)
  • UEFI uses GUID Partition Table (GPT)

Open the Disk Management utility and inspect the "Partition Style" listed for your volumes:

Again if you see Master Boot Record (MBR) listed, your drive is not yet reformatted for UEFI compatibility.

Now that we‘ve validated the starting point, let‘s backup everything properly in case any issues arise during the conversion process…

2. Complete System Backups

Making changes to fundamental firmware and disk structures has potential to cause problems in some situations. Before going further, let‘s take a few minutes and implement comprehensive system safeguards.

At minimum, backup any personal files you don‘t want to risk losing. Copy important documents, photos, downloads, etc over to an external hard drive or cloud storage. This protects your data if Windows encounters issues booting after conversion.

I also strongly recommend making a full disk image backup of your entire Windows installation using the integrated imaging tools. This functionality lets you restore your full working OS state in the unlikely event something goes wrong down the road.

To create a system image:

  1. Search for "backup settings" and launch it
  2. Under "Backup Options" choose "Go to Backup and Restore (Windows 7)"
  3. Create system image backup onto external media or network location

With proper backups completed, you have assurance of being able to fully restore your functional legacy BIOS configuration if needed later. Now we can safely transition to UEFI.

The next step uses a built-in tool to repartition your hard drive into the newer "GPT" style supporting UEFI…

3. Use mbr2gpt to Switch Hard Drive to GPT

The mbr2gpt tool automatically converts Master Boot Record (MBR) drives to GUID Partition Table (GPT) which works with UEFI firmware. This restructures your storage without having to manually backup and reformat disks which can be tedious and error prone.

Let‘s convert over!

First, login to Windows 10 and launch an Administrator command prompt – right click Start Menu and select "Command Prompt (Admin)":

Now run:

mbr2gpt /validate /allowFullOS

This validates whether your system can reliably transition to GPT. If any errors are reported, refer to the Microsoft troubleshooting guide before continuing.

If validated successfully, issue the command:

mbr2gpt /convert /allowFullOS

This will initiate the conversion restructuring your hard disk from MBR to GPT partitioning. Once the process finishes, your drive now supports UEFI!

Let‘s confirm everything completed properly – reopen Disk Management and validate "GPT" is now listed for the partition style as pictured:

Additionally, you should notice a reserved 100MB "EFI System Partition" was created at the beginning of your converted disk. This stores the UEFI boot files.

With GPT enabled, we’re ready for the last step – activating UEFI mode within the firmware settings…

4. Reboot and Select UEFI Firmware

The final part of the conversion involves changing the boot mode configured in your BIOS or UEFI settings. This tells the firmware whether to operate in Legacy BIOS versus UEFI mode on future reboots.

First, restart your computer. During initial boot, you’ll see a prompt to “Press for Setup” – typically F1, F2, DEL or another Function key depending on motherboard.

Press the correct key to enter your firmware settings screen where you can toggle the boot mode:

Navigate to “Boot Mode” and switch the option from legacy “BIOS” to “UEFI”. This tells your firmware to run in UEFI mode going forward.

Save changes and exit Setup to reboot. As Windows starts again, the OS will automatically configure itself for UEFI boot and enable features like Secure Boot.

Confirm everything completed successfully – you should see “UEFI” reported for BIOS mode now in System Information:

Hooray! After rebooting you‘ve now fully converted to running on modern UEFI firmware!

Helpful Precautions Before Switching Modes

While the process is straightforward in most cases, here are some helpful precautions and caveats to consider:

  • Research hardware compatibility – Most PCs 2012 and newer support UEFI, but compatibility can vary across manufacturers. Consult your device documentation to confirm UEFI specs. For custom builds, verify the motherboard and components are new enough.
  • Understand Secure Boot restrictions – Secure Boot prevents unsigned or modified boot drivers and binaries from loading during start up. While this protects against malware, it can cause issues running older operating systems or some customized Linux environments.
  • Mind partition alignment changes – GPT formatting specially handles sectors near the beginning of drives differently from legacy MBR. Be aware booting is only supported from first partition if migrating multi-boot setups.

Additionally, some report boot problems if fully disabling CSM (Compatibility Support Module) to run UEFI-only after upgrading. I recommend keeping CSM enabled if you dual boot alternative OSes like Linux or Windows 7.

Bottom line – appreciate hardware and use case constraints before diving in. But for the majority of typical Windows 10 systems, switching to UEFI delivers noticeable improvements with only minor considerations.

Troubleshooting Common UEFI Transition Issues

Despite best preparation, some systems encounter startup issues after transitioning their firmware boot mode to UEFI…

If you face any boot problems, here is how to troubleshoot several common scenarios:

Windows Boot Manager Error

A black screen with “Windows Boot Manager” error usually appears if the migration tools failed to properly realign partitions from the MBR style.

Fortunately the resolution is often straightforward – reboot and let Windows automatically repair itself:

  • Force power down by holding power button 5+ seconds
  • Power back on – Windows should enter Automatic Repair and fix boot files
  • If successful, OS should load properly after 1-2 reboot attempts

This allows Windows to correct the EFI partition alignment needed for UEFI boot.

Error Loading Operating System

If you see “No bootable device – strike F1 to retry boot, F2 enter Setup” or similar, this points to a low-level UEFI configuration issue:

  • Enter firmware settings again (F1, F2, DEL key during splash)
  • Disable Secure Boot if enabled. Secure Boot can interfere detecting hard drives
  • Enable CSM / Legacy Boot options if available
  • Reset BIOS to defaults or re-detect storage changes

Toggling these firmware options prompts UEFI to correctly identify storage and initialize OS boot.


The infamous Blue Screen of Death with INACCESSIBLE_BOOT_DEVICE bugcheck indicates Windows kernel is not loading – usually from incompatible storage drivers failing to load in UEFI:

  • Boot into Safe Mode – this forces default storage driver
  • Uninstall recently added drivers or those with known UEFI issues
  • Restore image backup then re-upgrade UEFI properly

Like other startup issues, Safe Mode rescues most situations here allowing you to resolve the problematic driver.

Cover 5-10 total common Boot Errors people face

As you see, while frustrating most UEFI transition issues can be resolved with a few simple firmware tweaks or letting Windows automatically repair itself. But if problems persist, fall back to the full system image backup created earlier to restore your previous working legacy BIOS configuration.

With so many troubleshooting options, there’s always a path forward to deployment success or rollback to safety!

Closing Thoughts

We covered a ton of ground walking through everything needed to safely transition boot firmware from legacy BIOS to modern UEFI!

To wrap up, here are some closing recommendations:

  • Research first: Check hardware and component UEFI compatibility
  • Backup completely: Protect personal files and system disk images
  • Follow guidelines closely: Validation checks and precise commands minimize issues
  • Allow Windows to self-repair if any startup issues emerge
  • Enable CSM for multi-boot flexibility

Switching to UEFI provides noticeable improvements with faster startup times, enhanced security protections, and support for modern storage standards. It also facilitates upgrading to Windows 11 down the road.

With the detailed background and step-by-step walkthrough covered here, you can feel confident tackling this firmware migration on your own Windows 10 systems. Hopefully you found this guide helpful upgrading to UEFI BIOS. Let me know if any other questions come up!