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

  • dodg036 November 20, 20171:16 am

    Xeon L5420. Installed in the system administrator from HP dx7500. It started without changing the BIOS. Modification of the BIOS causes the windows7 to boot only in safe mode. And without modification the system of hunting works at a maximum. bios AMI 5.14.

  • Baki November 26, 201711:51 am

    Upgraded Asus P5B motherboard with latest bios 2104 + added microcode for lga 771. Works perfectly.

  • leeloo December 16, 20179:45 pm

    Im looking to use a “Xeon E5540” cpu-world says the cpuid is 106A5 a microcode for that id not included in the zip provided here but I have been told the CPU works with my board. anyway poking around I actually found a 2015 microcode for the CPUID but the platform is listed simply as “03”

    if LGA711 is 4 40 44, LGA755 is 1 10 11, mobile is 20 80 or A0 what is 03? will 03 work on a 755 board?

    MMTOOL says my bios already has a massive range of different platform numbers and 03 is one of the microcode already included in the official rom! (to list a few others 01 to 11,32 5C DB 9D F5 25)

    the E5540 uses the same architecture as the first gen I7 9xx series but the id would still be unique to this cpu right? does the platform in this case matter? suggestions please because I have no idea?


    • leeloo December 16, 201710:05 pm

      nevermind I think cpuworld has the wrong cpuid listed, they have it as 1366 and not 711 unless there are 2 different version of the E5540, I will just have to hope it boots without a microcode so I can get the actual cpu id

      • leeloo December 16, 201710:09 pm

        found it was on the wrong page please delete >_<

  • Ed January 22, 20187:31 am

    Hi i’m using an intel DP43TF and a Xeon E5430 but i got a problem, i think i can’t update the microcode for the cpu, some can help me ?
    I don’t know how to put the microcode because it seems that i can’t use mmtools and “We don’t currently know of any microcode updating guides for Intel BIOSes”
    So i don’t know what do to :/

  • Bruno Melo February 11, 20181:54 pm

    Hi guys,

    I have MSI G41M.P33 Combo and installed an already modded xeon E5450, but after i flashed the modded bios (with the 2 microcodes cpu0001067a_plat00000011_ver00000a0b_date20100928 and cpu0001067a_plat00000044_ver00000a0b_date20100928), the system runs very slow even on boot.
    I need this modded bios to install windows 10 x64, without it he gets stuck at windows logo during installation.

    My System is:

    OS: Windows 10 x86
    MOBO: MSI G41M-P33 Combo
    CPU: Intel Xeon E5450 3.00GHz
    GPU: Nvidia Geforce GTX 750 TI 2gb
    RAM: Corsair 4gb 1333 (reduced to 1066)
    HDD: Samsung 250gb
    PSU: Eurotech Silent Pro 580w
    CPU Cooler: Thermaltake MaxOrb

    Note: System runs fine with the original bios (without xeon microcodes).

    • Stepa February 12, 20181:42 am

      Do you use the Xeon E5450 revision E0 (CPUID 1067A)?

      You can try a newer microcode from here: https://github.com/platomav/CPUMicrocodes/tree/master/Intel
      It is enough to add only one microcode * _plat00000044_ *

      • Bruno Melo February 12, 20186:26 am

        Hi Stepa, thks for your reply,

        Yes i use the Xeon E5450 revision E0 (CPUID 1067A), and i already tried to add only the 44 microcode but was the same thing, i even tried to use the already modded bios for my MOBO from this link “http://genius239239.myweb.hinet.net/771/” and still the same thing.

        I’ll try one more time with the new microcode of the link you sent me, thks.

        Best regards.

  • Mustafaa February 12, 20187:39 am

    I have just updated microcodes in my BIOS. Works like a charm! Main board Gigabyte P35-DS3. Updated using F14 BIOS version and full microcodes package. Now I can fully use my Xeon E5450. Thank you so much for this guide!

  • Frank February 14, 20184:00 am

    I have a Dell bios, and I can’t see what I’m supposed to do once I downloaded the microcodes and extracted the bios update. How do I put the microcodes in the update? How do I update since I extracted the executable?

    • Stepa February 14, 20181:44 pm

      Check the unpacked BIOS with the intelmicrocodelist. Does the program find the old microcode?

      • Frank February 14, 20182:10 pm

        Thank you for the reply, but I’ve just discovered the motherboard has a chipset incompatible with my x5460. Sorry, I’ll try again when I manage to get another cheap motherboard…

  • Tryant February 18, 20181:18 pm


    I bought a Xeon E5450(premodded) and installed it on my MSI P965 Platinium
    It does go to bios and post screen it also recognises it as a xeon e5450.

    But when the windows logo appears it loads for a few second and then reboots.
    It also does this when I try to reinstall windows from usb.

    Tried bios reset no change.

    Wanted to update the microcodes but the bios is a .180 file and a .exe
    Tried changing the .180 to .rom but mmtool still does not recognise the file. (error loading firmware image)

    • Stepa February 25, 20187:53 pm

      Just rename A7238IMS.180 to A7238IMS.ROM and open it with MMTOOL.

      But the problem can be that the motherboard supports only processors with CPUID 10676 (Rev. C0). If you are using a newer revision of CPUs with CPUID 1067A (E0), then it can be unstable.

  • JOnas February 27, 20186:13 am

    Once I have modded the rom file i extracted from the dell bios exe file how do I go about flashing the motherboard with this rom file

    thanks in advance

  • JOnas February 28, 20188:17 am

    Updating microcode hasnt allowed to use virtualisation.


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