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

  • Guilhem Vergon February 25, 20195:39 pm

    Got it working on a Gigabyte G41-M Combo motherboard, and a X5460 CPU oc@3.3GHz.

    Got it working flawlessly adding CompareExchange128, it now runs games like the latest Tomb Raider (Shadow of…).

    BUT !

    I still cannot find information about how to add AVX instructions so I can play the latest Assasin’s Creed Odyssey.

    Do you think VT-x would rule the problem ?

    Any clue here… ?

    • sijin July 6, 20191:24 pm

      How to install bios microcodes to gigabyte g41 with xeon e5450?

      • Guilhem Vergon February 29, 20205:09 am

        Everything is written up here ^ I just followed the tutorial (and I’m not too good !)

    • BB February 8, 20207:51 am

      i have this mobo and a x5450 did you solve the game issue’s you mentioned?

      • Guilhem Vergon February 29, 20205:11 am

        Nope, the 771/775 is not able to deal with AVX instructions, you have to upgrade to sandy bridge platforms (at least)

        • BB April 9, 20204:34 am

          sandy bridge platforms!, ok no probs!, i prefer tomb raider anyhow!… so i’l just avoid those game that want that avx i set.

          ps just waiting on tape strips to arrive now.

          • Guilhem Vergon April 9, 20204:58 am

            To me you should prefer ivy bridge with a LGA 1155 setup, you can build a cheap setup for less than 150$ (cpu ~40, MOBO ~60, 12-16go RAM for ~50). I built something comfortable with a z77 gigabyte mobo,Xeon E3-1230 V2 and 3x4go Crucial DDR3 1600.

            Ivy bridge has the undeniable advantage of a very low power consumption with only 69W, and deal with AVX instructions !

  • Januar May 24, 201912:07 pm

    Please help me,
    After update using modified bios by microcode fo optiplex 760 my system not recognized the cpu.
    It show “the current system does not support the cpu”
    how to fix it . thanx

    • adal July 11, 20192:56 am

      disculpe ya lo soluciono y que procesador usa? y me podria pasar la bios la necesito para un x5460

  • Asi. May 27, 201910:57 am

    I have intel desktop board DG41WV and have update BIOS in latest version, i installing Xeon CPU X5450 and it works fine, but i can’t restart !
    How i can have the microcode for this CPU to fix that?
    thx for your help

    • Excly July 22, 20203:07 pm

      Hello did you ever solved that problem?, i have one and want to try it

  • Amir June 22, 20198:42 pm

    Helo iam use msi motherboard with xeon e5450
    But went i check at system only show 2cores only….
    What should i do to make out 4 core like cpu use to be

    • Carson July 21, 201910:10 pm

      Maybe try going into msconfig and see if all cores are enabled.

  • franklin lovo June 26, 20196:02 pm

    una pregunta chicos tengo una placa base p5p43td y quería saber si para hacer el mod a xeon tengo que cambiar de bios o solo le corto la patitas del lado a la pc y pongo por defaul la bios y monto el procesador..

  • sijin July 6, 20191:26 pm

    How to install bios microcodes to gigabyte g41 with xeon e5450?

  • Gabriel August 16, 201910:21 am

    Some one guide me to mode MSI G41 p26 mobo..

  • Dawid August 19, 20194:50 pm

    Witam czy będą mikrokody do Xeona E5450 do płyty głównej na chipsecie Q45/Q43
    Jest to komputer HP dc7900e

  • Gonalo August 29, 20194:07 am

    Mi bios es 786C2 v01.07 como actualizo? el enlace esta roto.

  • Adlan November 7, 201910:38 pm

    How can i update my bios but with a different extension ? in his case the extension is.exe not .rom ? i’ve been searching on internet looking for my bios motherboard Gigabyte GA-G41MT-S2PT, but all the extension for the bios is .exe not .rom, how can i flash it ?


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