How to flash a BIOS safely, on old and new boards

Here is how to flash a BIOS safely, in short. Update only when the new release fixes something you need. Identify the exact board model and revision, download the file from the board maker's own support page and read its release notes. Save whatever copy of the current firmware your board allows, and write down your settings. Then run the maker's flasher from inside the BIOS setup, on steady power, and do not touch the machine until it reboots by itself. Load defaults afterwards and check the version number. That is the whole method on a 2008 LGA 775 board and on a current one; what changes between eras is which tool you use and how much of a backup you can take.

When to flash, and when to leave it alone

A BIOS update is worth the small risk when it does one of these things:

• Adds support for a processor you want to fit. Board makers publish a CPU support list with the minimum BIOS version for each chip. Our guide to checking whether a board supports a processor shows how to read one.
• Fixes a bug you actually have, and the release notes say so.
• Carries microcode or security fixes. Microcode is the patchable layer inside the CPU, loaded by the BIOS at every power on; see what CPU microcode does.
• Is a stated prerequisite for something else, such as newer management engine firmware.

It is not worth it when the machine runs well and the notes list nothing that applies to you. MSI's own flashing page says so in capital letters: do not flash when your system is running fine. Skip beta releases on a PC you depend on.

Identify the exact board and revision

The download has to match the board exactly, and a near miss is the classic way to brick one. Model names that differ by one suffix (PRO, PLUS, WIFI, a trailing D3) are different boards with different files. Revisions matter too: Gigabyte publishes separate pages per PCB revision, and MSI tells owners to find the MS number and version printed on the board between the expansion slots and to confirm the BIOS version in setup before downloading.

Write down the model and revision, read off the PCB if you can, and the BIOS version the board runs now, from the main page of the setup screen. The support guide above lists PowerShell and Linux commands for both.

Download only from the maker, and read the notes

Every major board maker serves BIOS files from the model's support page (on ASUS, the Download Center under Driver and Utility, then BIOS and FIRMWARE). Use those. Files from forums, driver sites or third-party "BIOS update" utilities are where corrupted and wrong-board images come from.

Read the release notes on the download page before you pick a version. Look for:

• Version order rules, such as "update to version X before installing this one".
• Firmware that has to be updated alongside it. ASUS, for example, tells owners of some 400-series boards that the Intel ME firmware must be version 14.1.51.1528 or newer before they update for 11th-generation CPUs.
• Warnings that a release cannot be rolled back.

Then unpack the download and look at what you have. An ASUS package holds a .CAP file; a Gigabyte file carries the version as its extension, such as .F1; MSI ships a folder. If the archive contains a file that does not match your model name, stop there.

Back up what you can

How much of a backup you can take depends on the board's era, and the difference is large:

On older boards, take the backup and copy it to a second place, so one dead stick cannot take your only copy. On current boards where the vendor tool refuses, keep a copy of the exact BIOS file you are running now, downloaded from the same support page, so you can flash back if the release notes allow it. For a byte-for-byte copy of any SPI chip, reading a BIOS chip with a CH341A programmer walks through it.

Also photograph or write down the settings you changed from default: boot mode, SATA mode (AHCI or RAID), memory profile, fan curves, any virtualization switches. A flash usually ends with defaults loaded, and a system drive set up in RAID mode will not boot if the controller comes back in AHCI. If the system drive uses BitLocker, have the recovery key on paper and suspend BitLocker before you start. ASRock's flashback guide warns that the update resets the TPM and tells owners to suspend BitLocker first; skip that and Windows asks for the recovery key at the next boot.

A small, plain USB stick is the one you need on the day; an external programmer and a spare coin cell are for the day something goes wrong.

Pick the flashing method: setup screen, DOS or Windows

There are three places a flash can run from, plus the flashback buttons on many recent boards.

The in-setup tools win because the operating system, its drivers and its updates are out of the picture while the chip is written. Gigabyte's manual for its Windows tool asks you to close all applications and resident programs first, which tells you what can go wrong there.

DOS still has a place on old hardware, when setup will not open or the board predates built-in flashers. The DOS command prompt guide covers drive letters and cd. For Award boards, follow the instructions that came with your BIOS package, because AWDFLASH switches differ between versions.

How to flash a BIOS without drama

The session itself is short. Prepare it so that nothing can interrupt it:

1. Prepare the stick. Format a USB stick as FAT32 (ASUS also accepts FAT16) with a single partition. Smaller sticks cause fewer surprises; the ASUS P5Q WS manual limits CrashFree BIOS 3 to sticks smaller than 8 GB. Put the file at the top level of the stick, not buried in subfolders.
2. Return to defaults first. Remove overclocks and undervolts, and load the optimized defaults. ASUS's update guide asks for the defaults to be loaded around an EZ Flash 3 update, for compatibility and stability.
3. Settle the power. A desktop belongs on a UPS if you have one. Otherwise pick a quiet moment on an outlet that does not share a circuit with a space heater, and do not start during a thunderstorm.
4. Start the tool and pick the file. Read the confirmation screen: the board name and the version shown should match what you expect. If the tool says the file does not match the board, believe it.
5. Leave it alone. Do not press keys, do not reset, do not remove the stick. MSI notes that the keyboard and mouse are locked during an M-Flash update anyway. ASUS, MSI and Gigabyte all repeat the same instruction: do not shut down or reset while the BIOS is updating.
6. Let it reboot by itself. Some boards restart more than once. Gigabyte's manual describes DualBIOS boards that, after a Q-Flash Plus run, reboot once the main BIOS is written, update the backup chip and then reboot again.

On an old board, add one step before all of this: write down the BIOS version shown on the POST screen and keep the old file next to the new one on the stick. If the new release misbehaves but the board still reaches setup, you can flash back from the same stick, provided the release notes do not forbid a rollback.

After the flash

Go into setup and check that the main page shows the version you installed; ASUS and MSI both list that as the final step. Then load the optimized defaults. Gigabyte gives the reason: the system re-detects all devices after a BIOS update. Restore your settings from the notes, check the boot drive and boot mode, start the operating system and resume BitLocker. If the system is unstable afterwards, load defaults once more before you blame the new release.

If it goes wrong

Do not cut the power in the middle of a write in the hope of starting over. Wait until the tool reports a result.

If the write finished but the board will not start, clear the CMOS with the jumper or by removing the coin cell for a minute, as page 4 of the LGA 771 to 775 guide describes, and try again. After that, work down the recovery routes your board has:

1. A second BIOS. Gigabyte's DualBIOS takes over from a backup chip if the main BIOS is damaged. Some MSI boards have a Multi-BIOS switch, and MSI documents running M-Flash from the good chip to rewrite the bad one.
2. Automatic recovery. ASUS CrashFree BIOS 3 looks for a BIOS file on a stick or the support disc when the BIOS checksum is bad and flashes it.
3. A flashback button. On boards that have one, it writes the chip from a USB stick with the system off.
4. An external programmer. A CH341A with a clip rewrites an 8-pin SPI chip directly, after the voltage checks in the CH341A guide linked above.
5. The maker's service. ASUS's own troubleshooting ends with contacting a service center, a legitimate last step.

A modified image, such as one with added microcode for a modded Xeon, follows the same procedure with higher stakes; the AMI and Award microcode guides cover building and checking one. For a plain official update, keep the old file, the new file and your settings note in one folder, labeled with the board's model, revision and date.

Sources and further reading

• MSI, How to flash the BIOS (model number on the board, DOS and M-Flash methods, the warning about flashing a working system)
• MSI, How to update BIOS? (M-Flash steps, confirming the version afterwards)
• ASUS, How to use USB BIOS FlashBack? (including the ME firmware note for 400-series boards)
• ASUS, Motherboard BIOS Update and Management (EZ Flash 2 and 3, CrashFree BIOS 3, BIOS Updater for DOS)
• ASUS, P5Q WS user manual (EZ Flash 2, AFUDOS and CrashFree BIOS 3 on an LGA 775 board)
• Gigabyte, Unique Features manual, X570 series (Q-Flash, @BIOS, DualBIOS, Q-Flash Plus)
• ASRock, Flashback Feature user guide (TPM reset and BitLocker)