LGA 771 Xeon Microcode – How to MOD Your BIOS



In this guide, we'll cover how to add the LGA 771 Xeon microcode to your BIOS. This is sometimes necessary for people doing the LGA 771 to 775 MOD.

Note: Microcodes are current as of 2018-12-02 (source). They were last updated by Intel on 2015-08-02.

How will updating the microcode help?

It can restore missing CPU instructions

If you did the LGA 771 to 775 MOD and notice missing CPU instructions (such as Speedstep, SSE 4.1, VT-x, or CompareExchange128) adding the Xeon microcode will usually restore that functionality.

It can also improve system stability

Microcode updates usually fix bugs or add new features, so by updating the microcode, you can sometimes make your system more stable.

LGA 771 Xeon microcode guides

Important: Make sure you do a FULL BIOS reset after updating your microcode.

If you have an Award, Phoenix, or AMI BIOS, the guides shown below should cover everything you need to know to add the LGA 771 Xeon microcode to your BIOS.

How can I tell what type of BIOS I have?

You may see the BIOS type when you turn on your computer or enter the BIOS. If you don't, you can use a program called CPU-Z to look this up (it should be listed as BIOS Brand in the Mainboard tab).

Note: AMI is short for American Megatrends Inc., so you may also see it listed the long way.

LGA 771 Xeon microcode files

Note: You don't need to download any of these files if you're using one of the guides shown above (they already have the correct microcode files).

  • Desktop LGA 771 and LGA 775 microcode
    • If you're trying to add LGA 771 Xeon support to an LGA 775 motherboard, this is the recommended file to download. It will allow you to not only add the LGA 771 Xeon microcode to your BIOS, but you can also update your processor's similar LGA 775 microcode (which is probably a good idea).
    • Contains microcode for all Core 2 Duo and later desktop processors (no Pentium 4 or mobile support).
    • Also contains the LGA 771 microcode shown below.
  • LGA 771 microcode

When you unzip one of these files, you'll see a bunch of individual microcode files that have filenames like this:


Here's what the different parts of the filename mean:

  • cpu0001067a - 1067A is the CPUID that is supported by this microcode
  • plat00000044 - plat is short for platform. This tells which sockets are supported by the microcode.
    • LGA 771 microcodes have a 4, 40, or 44 in this section
    • Desktop LGA 775 has a 1, 10, 11, B1, or 91
    • And for mobile LGA 775 it's a 20, 80, or A0
  • ver00000a0b - a0b is the version number
  • date20100928 - 2010-09-28 is the date the microcode was last updated

Which microcode files should I set aside?

You'll want to set aside all of the microcode files with your processor's CPUID (how to get the CPUID). There should be at least one of these for each platform, and you should go ahead and update the microcode for all of the platforms that you want your motherboard to support.

Note: If your CPUID ends in an "h" and you don't see microcode with an "h" on the end, just ignore the "h" because it isn't actually part part of the CPUID. That just means it's a hexadecimal number.


So for our E5450 (E0 stepping SLBBM) with a CPUID of 1067A, here are the LGA 775 and LGA 771 microcode files with a CPUID of 1067A:

  • cpu1067A_plat44_ver00000A0E_2015-07-29_PRD_A3107D75
  • cpu1067A_platB1_ver00000A0E_2015-07-29_PRD_59BF808E

If you have that processor and want to add the LGA 771 microcode and update LGA 775 microcode (which is recommended), you'd want to set aside both of these files.

What to do if you don't have an Award, AMI, or Phoenix BIOS

Insyde BIOSes

If you have an Insyde BIOS, there's a more advanced guide on manually hex editting a BIOS to add microcode. It is available here.

Intel BIOSes

We don't currently know of any microcode updating guides for Intel BIOSes. We've also heard that Intel may be using a secure checksum to prevent people from modifying them. If this is the case, it would prevent the manual hex editing method used for Insyde BIOSes.

Dell BIOSes

Dell often makes their BIOS updates available in an .EXE file that cannot be extracted by regular unzipping programs, so you'll need to use the trick shown below to extract it.

How to extract the BIOS ROM file from a Dell .EXE file

You can extract the actual BIOS from a Dell .EXE file with the following command:

DellBiosFilename.exe /writeromfile

This needs to be done from a DOS command prompt window.

Other BIOSes

If you have a different type of BIOS, you may be able to update the microcode by manually hex editing the BIOS. If you're interested in trying that, read the Insyde BIOS modding guide.

You may need to update the microcode in multiple places

If you're hex editing your BIOS to update the microcodes, we've noticed that some BIOSes have the same microcode in multiple places. If that's the case with your BIOS, make sure you update the microcode in all of the locations. Otherwise, it may not work.

Where to go for help

If you have questions about updating an Award, AMI, or Phoenix BIOS, leave a comment at one of the guides mentioned earlier.

If you need help with a different type of BIOS, we recommend asking for help at the following places: bios-mods.com, overclock.net, or forums.mydigitallife.info.

194 Responses

  • Алексей August 8, 20184:57 pm

    Здравствуйте у меня материнская плата intel DG33FB помогите модифицировать биос под 771 сокет

  • Андрей August 17, 201811:34 am

    Добрый день Алексей,

    вашей материнской карты среди протестированных нет, ближайшая материнская карта которую тестировали была Intel DG33FBC


    исходя из сопровожающей записи CPU Xeon E5450 и Xeon X5460 не запустились.

    В секции о совместимости есть следующая записка относительно материнских плат компании Intel
    Issues with Intel brand motherboards

    Note: This information only applies to motherboards actually manufactured by Intel. We haven’t heard of any problems with ASUS, Gigabyte, MSI, or any other brands.

    Some motherboards made by Intel don’t work with this mod
    For some reason, some Intel brand motherboards that have a compatible chipset and support a similar LGA 775 processor do not work with this mod (please see the list of tested motherboards for the model numbers).

    It may not be possible to update the CPU microcode on an Intel brand motherboard

    This is sometimes needed to install Windows 8.1 64-bit or to enable all of the CPU features (like Speedstep, SSE 4.1, or VT-X). The older non-E0 stepping processors often don’t need a microcode update to enable these features, so if you do try it, buy one of those.

    The reason this may not be possible is because Intel has their own proprietary BIOS that nobody currently knows how to MOD (even by manually hex editing the BIOS).

    Совместимость материнских карт для модификации BIOS


    Возможно кто-то вам сможет дать больше информации относительно модификации BIOS для вашей материнской карты.

    Вебсайт уже модифицированных BIOS для материнских карт Gigabyte и Asus


    другой вебсайт с модифицированными BIOS (организация веб страницы требует улучшения)



  • TommyTosser August 28, 201810:02 am

    I’ve also installed a Xeon on a 775 socket.

    But I’ve got a strange problem.

    The motherboard is an ASUS p5kpl-am epu and the CPU is an X5450 3.00Ghz.

    Everything works fine, it boots up, the bios recognizes the CPU, windows too.

    The thing is it doesn’t work past 2.50Ghz… What could be causing this?

    Its also working hot, close to 70ºc.

    • M. September 1, 20188:07 pm

      Most likely thermal throttling

    • Mruczyslaw October 23, 20182:12 pm

      Check if this cpu is running on same clock speed at bios. If in bios it’s 2.50ghz so you should set clock speed manually. If speed in bios is accurate, check if you have speedstep option turned off because it can limit clock speed when your cpu usage is low in OS. Also a temperatue like 70°C shouldn’t thermal throttle this cpu yet, I was using X5460 on nearly 100°C with no problem at all, but hot chipset or mosfet can be thermal throttling your cpu, unfortunately there’s no temperature sensor on that to check it, you can do it only by yourself, if it’s hot just add some small fan on it. There’s also a compatibilty issues because none of standard core 2 quad processors (I mean non-extreme ones) that have that big power consumption as 120W TDP which your X5450 have. I tried my X5460 on small pc Acer Aspire X3810 and there was also only 2.50GHz with no any option to fix this, but on my Asus P5QL-VM EPU it works with no problem and I was even able to overclocked it a little bit.

    • Mruczyslaw October 23, 20182:13 pm

      And of course update your bios to version with microcodes if you haven’t done this yet.

  • arevalosk5 September 13, 201810:00 am

    Hola. Compré un procesador Intel Xeon E5450 en un Aliexpress, que, de acuerdo con la descripción TDP 80W Comprado para la instalación en la placa madre Biostar G41D3C Ver. 7.0., Que de acuerdo con la especificación: CPU máxima TDP (potencia de diseño térmico): 95 vatios.
    Revisé el BIOS para instalar Xeon. Al inicio se muestra el mensaje: La potencia máxima de la CPU sobre 95W. Prepárese para apagar … cuenta desde 8 segundos y se apaga.
    La pregunta es, como hago para solucionar este problema?

  • Rayhan October 4, 20189:30 am

    I downloads microcode and mmtools from here, mmtools can run Properly. Microcode are bin files ican’t open with mmtools when i change .bin to .rom mmtools becomes error what should i do?

  • Rayhan October 4, 20189:36 am

    I downloads microcode and mmtools from here, mmtools can run Properly. Microcode are bin files ican’t open with mmtools when i change .bin to .rom mmtools becomes error what should i do?
    I use ecs g41-m12 motherboard

    • Franklin Zelch November 16, 201810:48 pm

      @ Rayham, I did not see your motherboard listed in the ‘tested motherboards’ section of this website. However, they do have the ECS G41T-M12 listed as “not tested yet”. There is also the ECS G41T-M7 (rev. 1.0). Both of those MB’s use the same chipset of G41/ICH7 which I assume your mb uses. For all the motherboards I’ve used socket 771 Xeon processors in I’ve only had to install the latest BIOS from the manufacture, I’ve never had to update the microcode manually to use the xeon cpus.

      • Nicolas January 6, 20199:15 pm

        Franklin Zelch, Hi. I hope that you can help me. I trying to run a xeon e5440 in ECS G41T-M7 (rev. 1.0). First I put the processor without touch anything of the BIOS or something else. Didn’t work. Give me a BSOD with the error DPC Watchdog violation error. So I want update the BIOS, but I don’t know what version is correct, because the CPUZ give me the following information:
        Model: G41T-M7 1.0
        Version: 080015
        Date: 1/12/2011

        And in the ECS page, the last version have the date 09/02/2011. So I’m not sure how I can procede with this. Can you help me? And sorry for the bad english, isn’t my language. Regards.

  • Buhmann December 4, 20183:26 pm

    Hello there.

    I’m running a Xeon E5450 SLANQ (C0 stepping) on a Abit IP35 pro. The processor works fine at stock speed (cpu features, speed steeping, all ok). As soon as I make changes in the BIOS µGuru or OC Guru (even it it’s just activating Fan EQ) and save the settings, the PC would shut down and with the next boot, all changes made in µGuru menu are omitted. Every other changes in my BIOS are applied and saved. But somehow I can’t configure anything in the µGuru menu.

    Has someone had a problem like this one and fixed it?

    BIOS is up to date and has all relevant microcodes.

  • Henrique December 12, 20188:34 pm

    I can not get the xeon to run on my GA-P35-DS3 motherboard, it never starts the windows, sometimes hangs on the motherboard logo, and most often stops on the screen that appears a lot of writing (black background and white letters, and most of the time the writings are different), I can not also start a bootable device (to install windows), and many times when I’m inside the bios the computer hangs, I downloaded a bios by genius239239, I downloaded a bios in the motherboard site and I put the microcode, I have modified the backup of the original bios and I put the microcode, nothing works, I already tried to decrease the clock and increase the voltage of the processor, really I do not understand Whatever is happening, the Core2Duo E8600 works perfectly… Does anyone know what’s happening?

  • Khurshid January 21, 20191:24 pm

    Здравствуйте, у меня материнская плата asus p5e3 deluxe есть ли шансы запустить e5450?

  • Michal February 2, 20193:31 am

    I have Asus P5QL Pro, could I ask for microcodes for my motherboard.
    Do I have to install the newest BIOS?


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