What is “Flashing the BIOS”?

April 3, 2011 by . 11 comments

From time to time in the technology blogosphere and on Super User, I would hear the term “flashing the BIOS”. I always wondered what that meant, because I have been in and used the BIOS many times, and thought I knew most everything about it. So I decided to post a question on Super User, so I could understand exactly what flashing the BIOS means. I also asked what the benefits there are to flashing and whether or not it should be done from inside or outside of the operating system.

What is the BIOS?

User ongle said:

There is a chip in your computer that has bootup instructions (The Basic Input Output System). It tells your computer how to do very basic things, interact with some hardware, load the operating system, etc.

When you first turn on your computer, you see the BIOS starting to load the computer. This process is called POST, “Power On Self-Test”. During POST, the BIOS finds and verifies the system memory, activates and checks system devices, and locates boot devices, and then passes control to the operating system once these tests have passed. The BIOS also offers configuration settings such as te boot order, power-on password, and CPU settings.

To enter the BIOS setup, you typically press a key like Esc, F2 or F12 during the POST process. The BIOS configuration screen often looks like this, a plain-text screen with contrasting colors, making it easy to read:

an example of what the BIOS looks like

Flashing the BIOS

Ongle continues:

Flashing it means to update it with a new program. You shouldn’t do it unless you need to do so in order to fix something. If power goes out while flashing, you can be left with an unbootable computer.


Updating Firmware aka Flashing the BIOS

User grawity also said:

The process is usually done by using either built-in functionality of the old BIOS, or a MS-DOS-based program (booted from floppy), or more recently, a Windows program (which comes with a special driver to obtain access to hardware). Some motherboards come with secondary firmware on a separate chip, which kicks in if the main BIOS is corrupted (e.g. power failure during flashing). This firmware usually supports flashing the BIOS from a file in a CD or floppy disk.

Flashing the BIOS is akin to updating software on your operating system but is a different process because the BIOS software is stored, not the hard drive, but rather on a chip on the motherboard.

In order to update the BIOS, the software chip must be completely erased and updated with a flash utility; this is essentially the process known as “flashing the BIOS”. This is referred to as “flashing” because the BIOS code is stored in flash memory.

an example of a BIOS chip

an example of a BIOS chip

A superuser may want to update his computer’s BIOS for a number of reasons:

  • support for newer processors (this comes in handy especially for custom computer builds), the BIOS is tweaked to allow processors up to a certain speed, thus if the processor is upgraded or overclocked, the BIOS may need to be flashed.
  • support for larger hard drives and solid state drives. Believe it or not, the BIOS is configured to only accept HDD/SSDs only up to a certain size, thus the BIOS has to be updated in order to allow the HDD/SSD to be used.
  • BIOS bug fixes. Since the computer left the factory, the original manufacturer may have found bugs in the BIOS and released an update for the BIOS, thus it may prove beneficial to update the BIOS so that it may run more efficiently and smoothly.

The computer cannot boot without the BIOS, thus if the power supply goes out while the BIOS is being flashed, it can leave you with a permanently damaged BIOS, resulting in your computer becoming a useless box. Another way the BIOS can be severely damaged is if it is flashed with an incorrect update version.

In summary, super users should only flash the BIOS if there is a real need to do so. If you feel you have to flash your BIOS, carefully considering the pro’s and con’s of such a move and back up your data, it goes without saying!

Special thanks to nhinkle for his help with this post!

Filed under Question of the Week


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  • I was about to flash mine for the sake of it!!

  • Asa abdelhlaim says:

    I left my laptop for a minute when I returned there was a notice that my touch pad would not work during flashing. i did not know what flashing was, as in my 20 years of owning a computer i have never encountered it. I thought it could be something that worked automatically. A few minutes later the screen went black and the computer sounded like a car (only lower level of noise) it continued to do so for almost an hour. I tried to turn the computer off but it won’t go off, so i pulled the plug and removed the battery. a minute late I turned it on, and it asked for for an outside source of power, i plugged it in and it started to fix the “corrput BIOS” after finishing that the computer was back to its normal (self). How do i prevent this from happening again. I am by no means a “super” user. thank you

    • Bassdrop1 says:

      I have really no idea. HP just force flashed me and I didn’t really know what it was until now. It could be some sort of defect in the computer. All I know is, your very lucky your computer’s not a box now.

    • Fares says:

      touchpad will not work while flashing bios, you shouldnt have disconnected your pc next time you should leave it alone and wait till the flashing is over.

  • T. Wrecks says:

    Some motherboard manufacturers, such as Gigabyte, actually install 2 BIOS chips on the motherboard for just such an occasion. Evidently bad flashes happened enough to warrant the back-up chip. If you corrupt one, the other one boots right up. So, if you are into custom builds, and have an itch to tinker with BIOS, I would recommend deploying this type of board…

  • Adam Moore says:

    Good article! But, it’s not all info about flashing BIOS there are some other ways and cases when you need to use other approach: How to flash BIOS.

  • anonymous says:

    Perhaps a third party installed malware on your computer which flashed your bios. It is very, very unusual that your bios would just get flashed without your explicitly doing it. This is something that is underneath your operating system, for example windows would never touch your bios since the OS boots only once your BIOS is already running.

    I would be very suspicious of third party malware causing that bios flash. Watch the io9 video on the NSA. Google will find it for you.

  • sunilamco says:

    what is the flash system & its work??

  • malik says:

    Good Article, very informative !!!

  • Al says:

    I do this all the time with my FM2+ MB with UEFI BIOS, my TV set, and phone with custom ROM and kernel just for the sake of keeping everything up to date and fixing bugs that would otherwise go unnoticed. I never had a single problem with the process. As long as you correctly identify the product model and updating procedure before downloading the update in object, i don’t think you risk hard bricking any hardware at all. And, whenever the update you correctly applied is official and you are within warranty, if something goes wrong there’s still RMA.

  • amol says:

    thank you man!!! all needed knowledge in one page!! and also i left the thought to flash my bios..

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