How to Update CPU Microcode in an AMI BIOS – For LGA 771 & 775



In this guide, we'll show you how to update or add new CPU microcode to an AMI BIOS. If you have an Award or Phoenix BIOS, check out this guide instead.

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

Note: This information has only been tested with LGA 771 and LGA 775 BIOS files, so if you have a newer motherboard (especially UEFI ones), it probably won't work.

Why would you want to do this?

Updating the microcode is helpful if:

  • You did the LGA 771 to 775 MOD, and your Xeon is not working as expected (or is missing functionality, such as CompareExchange128, Speedstep, SSE 4.1, or VT-X).
  • Your BIOS doesn't support a newer processor that you want to run.
  • The microcode for your processor is old and may be buggy.


There's an element of risk just flashing a normal BIOS, and especially when you start modifying it, so please attempt this mod at your own risk (and only if you're experiencing some problem). We highly recommend that you don't flash the modified BIOS unless you've verified the microcode was added correctly. If you accidentally remove the microcode that your processor needs, your system may fail to boot. We are not responsible if your system is damaged while attempting this.

Things you'll need

Step 1 - Download the microcode for your platform

  • 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)
    • Contains microcode for all LGA 771 Xeon processors (except older Pentium 4 based 50xx models).
  • Desktop LGA 775 microcode
    • Contains microcode for all Core 2 Duo and later desktop processors (no Pentium 4 or mobile support)
  • Mobile LGA 775 microcode
    • Contains microcode for all Core 2 Duo and later mobile/laptop processors (no Pentium 4 or desktop support)
  • LGA 771 microcode
    • Contains microcode for all the LGA 771 Xeon processors mentioned earlier (no LGA 775 or mobile support)

Step 2 - Look up the CPUID for your processor

You'll need the CPUID to update the right microcode (how to get the CPUID).

What if I can't find the CPUID for my processor?

You can just update all of the microcodes.

Step 3 - Set aside the microcode files for your processor's CPUID

Note: If your CPUID ends in an "h" and you don't see a 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.

When you unzip the microcode file, 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. 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.


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.bin
  • cpu1067A_platB1_ver00000A0E_2015-07-29_PRD_59BF808E.bin

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.

Step 4 - Open your BIOS in MMTOOL by using the "Load Rom" button

Note: MMTOOL will only open BIOS files that end in .ROM, so if yours doesn't, just rename it to .ROM for now.

mmtool cpu patch window

Having trouble finding the BIOS rom file that you need to MOD?

If your BIOS is in an .EXE format

You'll need to first extract it with an unzipping program like 7-Zip. Then look for a file that ends in .BIN, .ROM, or possibly something else like a number. LGA 775 BIOSes are usually around 1024 KB in size, so look for a file about that size. You can also try to open the file in MMTOOL. If it isn't the right file, MMTOOL will let you know.

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

Execute the following command from a DOS command prompt window:

DellBiosFilename.exe /writeromfile

This should extract the actual BIOS file to the same directory. When you're done modding the BIOS, you can use a program called AFUDOS.EXE to flash a Dell AMI BIOS.

Step 5 - Click the "CPU PATCH" tab to access the microcode area of the program

You'll then see a list of all of your current microcodes.

Step 6 - If you're updating your old microcode, delete all of the old microcodes that match your processor's CPUID

Note: MMTOOL only shows the last 4 characters of the CPUID, so don't let that throw you off.

  • Select the option "Delete a Patch Data"
  • Click the microcode you want to delete
  • Click the Apply button

If your Xeon's CPUID is 1067A, then delete all of the microcode entries with a CPUID of 067A (there may be more than one due to different platform types).

Step 7 - Insert the new microcodes

  • Select the option "Insert a Patch Data"
  • Click browse and select the microcode you want to insert
  • Click the Apply button

Do this for all of the microcode files that have your processor's CPUID. You should have set these aside in an earlier step.

What should I do if I'm getting an error message that there isn't enough room for the microcode?

You'll need to delete some of the old microcodes to make room. Just make sure you keep the microcode for your old processor in case you ever need to reinstall it.

The microcodes with a CPUID of 066x (where x can be any letter or number) are usually older Pentium 4 and Celerons, so those are usually safe to delete. You can also search for the CPUID on cpu-world to find out which processors use that CPUID.

Step 8 - Click "Save ROM as.." to save your modified BIOS

Step 9 - Verify that the microcode was added correctly

Go ahead and close MMTOOL, reopen it, and load your modified BIOS file, which you saved in the previous step.

Navigate to the CPU Patch tab again, and make sure all of the microcodes that you added earlier are shown.

You should also check to make sure no old microcode for your CPUID is present. If it is, you'll need to go back and delete it. Otherwise, your system may use the old microcode instead of the new ones we just added.

Step 10 - Update your BIOS using the modified ROM file that you just created

You should be able to update it the same way you'd update a normal BIOS.

Not sure how to update your BIOS?

The method for updating your BIOS is different for each motherboard manufacturer.

  • With some, you can simply put the BIOS file on a USB key, reboot and enter the BIOS, and update it from there.
  • Others may have a BIOS updating program that you can run from within Windows.
  • And in some cases, you may need to put the BIOS on a bootable DOS USB key, CD, or DVD and update it from a command prompt.

If there's a Windows or DOS BIOS updating program, it will usually be included with the BIOS or mentioned when you download the BIOS. If you don't see it, check the downloads section, FAQ section, or support section.

If all else fails, try searching Google for your motherboard’s model and update BIOS or something like that.

Step 11 - Do a FULL BIOS reset (use the 3-pin motherboard reset jumper, and then load the default BIOS settings on the first startup)

How to fully reset your BIOS

263 Responses

  • greg June 13, 20143:11 pm

    asus p5k
    xeon e5430 with microcode works fine,o.c. at 3.206 :) :) :)
    8gb mem
    bus speed : 400.8
    rated fsb : 1601
    tnx all for the help and topics !!!!!

  • blkmail901 July 4, 20147:05 am

    Probably advised to put both 44 and 11 platforms

    • syn July 4, 20142:16 pm

      Yes, you should update all of the microcodes that have your processor’s CPUID.

      I’ve edited the article to make this more clear.

  • thestig03 July 7, 20143:34 pm

    Hi, I downloaded the latest microcode pack from the intel download center (microcode-20140624) but I can’t get the microcodes .bin files. When I extract it i get a microcode.dat file.
    Would you help to get the .bin files? I want to make the 771 mod with the latest microcodes.
    Thank you

    • syn July 7, 20144:04 pm

      Intel hasn’t updated the LGA 771 microcodes since 2010, so the ones we’ve included on this page should be the newest.

      However, if you still want to extract the microcodes yourself, the extraction tool is called microdecode.exe. It should show up on Google.

      • thestig03 July 7, 20146:20 pm

        I thought they where newer as the file name is 2014 06 24. Once the Xeon arrives i’ll try the mod and update my results on the post. Fingers crossed! haha Thanks!

        • syn July 7, 20149:58 pm

          Yeah, that’s the microcode file for all of Intel’s processors, so they update it whenever any new microcode comes out. However, the LGA 771 ones haven’t been updated since 2010.

  • sylvester nagy July 25, 20145:56 pm

    Hi i have intel xeon e5310 – SLAEM – i would like to used in asus p5kpl-am epu motherboard..

    Can you give me microcode?

    Thank you

  • jase August 13, 20145:02 pm

    Thanks guys

  • ym58 August 28, 20149:38 am

    Hi syn,
    I followed all your instructions and ended up with a mod flash Bios for a Dell Vostro 420 computer.
    Now it’s time to FLASH …. (at my own risk!)
    But the question is : HOW ?
    How can I flash this new MOD’ed BIOS.ROM to my PC ?
    Dell uses to provide a self-extracting/processing .EXE (from which I managed to get the initial .ROM file), but how can I do the opposite i.e. to generate a .EXE from my .ROM ?

    • syn August 28, 201411:14 am

      I know it can be done, but I’ve never tried it myself, so I’m not sure.

      I recommend asking for help at these places because they probably know how to do it:

      If you figure it out, please let us know.

    • ym58 August 28, 201412:14 pm

      Hey syn,

      I have found ***HOW*** !!

      There is a utility called AFUDOS.EXE that has been made specifically to flash the AMI Bios (Dell Vostro 4520 BIOS) from a BIOS mod .ROM file ….

      Unfortunately, the mods that I made to the DELL BIOS did not work as expected : my X5450 boots but with many flaws (slowliness, sometimes hanging and the likes …)

      I understand now why you didn’t publish any reports of successful Xeon porting to a Dell Vostro 420 MB (G45A01) !

      FYI, this is what I did :
      I replaced older CPUID 0676 platforms 01 and 10 (thats is 2) with newer CPUID 0676 platforms 01, 04, 10 and 40 (that is 4)
      and I replaced :
      older CPUID 067A platform 11 (thats is 1) with newer CPUID 067A platforms 11 and 44 (that is 2)

      To no avail :-(

      So, I went back to my former LGA775 Q8200 (without REflashing the initial BIOS) and it’s up & running again … but I wish I could have had the Xeon work !

      Should you have any hint, please don’t hesitate.


      • syn August 28, 201412:24 pm

        Hey, did you redo the stuff mentioned here ( after flashing the new BIOS? You’d probably need to fully reset the bios again (jumper + loading default settings).

        If that doesn’t help, I’d try the other stuff mentioned in the troubleshooting section (like disabling power saving features or reinstalling windows). Doing all of that stuff has fixed problems for probably 95% of people.

      • syn August 28, 201412:35 pm

        I think I remember you saying you loaded default BIOS settings to fix the running at minimum speed problem, but you really need to FULLY reset the BIOS by either using the reset jumper on the motherboard or removing the CMOS battery. You may have already done this, but the majority of people that have problems usually haven’t, so I just wanted to make sure. Then on your first bootup after resetting it that way, you should go into the BIOS and load the default settings.

        If that doesn’t help, then I’d do the stuff I mentioned in my previous message.

    • Oskar November 4, 20152:03 pm

      Hi ym58, I have a vostro 220 (uses same bios as 420), and im struggling with how to get the rom file out of the dell exe. How did you do this?

      • ym58 November 4, 20153:45 pm

        hello oskar,
        this is quite of an old topic and i think that i am no longer proficient enough to post any relevant advice here.
        hope you’ll find someone to answer your question … good luck !

        • Oskar November 5, 20153:44 pm

          Was able to sort out the microdes myself :) But now the machine is increadibly slow compared to my old E8400. But ill find a solution. Thanks for the reply.

  • ym58 August 28, 20141:11 pm


    Yes, of course I did the clear CMOS … first thing I did, actually !

    The former post where I mentioned that I just did a simple default loading was on another PC (a Vostro 220 with Phoenix BIOS) … and that did the trick really good at that time (last week).

    However, this very PC that I am on right now (Vostro 420 with G45A01 MB and AMI Bios) is really, really reluctant to make the Xeon work properly.

    And so far, if I read well, none of your fellow users has ever reported to be able to make a Xeon work on this MB.

    However, I will try the ‘Power Saving feature’ trick, even if I am not sure AMI Bios has this option.

    The point that I was not very sure is in my BIOS mod whereby I replaced 2 platforms with 1 platform (on CPUID 0676) and 1 platform with 2 on CPUID 067A … that sounded a bit odd to me, reason why I asked you.

    Strangely enough, the Xeon boots properly in Windows safe mode, but takes hours to boot in normal mode (I really mean hours, I have to stop the boot after 15min waiting, on a SSD !).

    Although it booted ***ONCE***, but only once (but the frequency was 2.3Ghz or so and not 3Ghz as it oughta be).
    Never been able te replicate this boot!

    • ym58 August 28, 20141:16 pm

      please read :

      the point that I was not very sure is in my BIOS mod whereby I replaced 2 platforms with ***4*** platform (on CPUID 0676) and 1 platform with 2 on CPUID 067A … that sounded a bit odd to me, reason why I asked you.

      • ym58 August 29, 20142:20 pm

        Once again, syn was bloody damn right !!!
        I went into the DELL Vostro 420 AMI BIOS configuration and found an ‘Advanced CPU settings’ menu featuring different options.
        A particular one is named “Speedtest” which needs to be ***DISABLED*** to have the Xeon 5450 work on this MB.
        But that’s not enough, though
        Once Speedtest has been disabled another option then appears in the BIOS that is named ‘Ratio CMOS setting’, sort of multiplier that handles the max clock freq for the proc.
        This ‘Ratio’ comes with a default of 9.
        If you leave it at 9, Windows will never boot and slowliness will plague the Xeon during boot.
        I first tried 6 and it worked but then the proc was quite slow in CPU-Z (2Ghz max), then I made successive tests and the machine will still boot with a value of 8.5 !
        The only (small) drawback is that the Xeon max freq in CPU-Z will show a value a bit less than 3Ghz (2.8Ghz, actually) … but that ain’t so bad compared to my former Q8200@2.33Ghz !
        So syn, you can amend your compatibility list with my own experience that is :
        Vostro 420 with AMI BIOS 1.3.0
        MB G45A01
        Processor X5450
        Disable Speedtest in BIOS and adjust ‘ratio CMOS setting’ to the higher acceptable value to make the machine boot.
        It ***MAY NOT*** require a BIOS mod (this I can’t say as I don’t want to revert to initial BIOS) but ***I DID*** modify the BIOS as per your tutorial.

        • syn August 30, 20142:22 am

          I’m glad you got it working. You may also be able to use an 8.5 multiplier to get a little more speed.

          Additionally, I’m not sure what’s causing you to need to reduce the multiplier. It could be a defective Xeon that isn’t stable at stock speed, or you may be right at the limit of what your motherboard can support power wise.

          • ym58 August 30, 20146:06 am

            I would say your second option is likely to be true since this very Xeon runs fine @3Ghz in another Dell PC (Vostro 410)

      • syn August 30, 20142:15 am

        Sorry for the delay in responding. It sounds like you did the microcodes correctly. The reason you added twice as many microcodes is because you updated the old LGA 775 microcodes and added the new LGA 771 codes.

    • Eric February 24, 20209:46 am

      Check the driver graphic are not doubled, in safe mode.

  • ferrel hunt September 2, 201410:57 am


    Using MMTool: Tried to add Xeon code to foxconn g33m bios update. When i hit “apply” everything changes from intel codes to amd codes?????
    Tried .rom file that a friend had already modified, and it will let me add codes?????
    I’m real new at this.

    • syn September 2, 201412:15 pm

      Hmm.. by changes to AMD codes, do you mean the Vender on the CPU Patch screen changes to AMD? I’ve never heard of that happening before.

      I’m not sure exactly what to do to fix it, but I’d try rebooting and redownloading the BIOS, microcode, and MMTOOL. If that doesn’t help, it’s also possible the program may not be compatible with your specific BIOS.

      If I think of anything else, I’ll let you know. If you figure out what the problem is, please let me know.


      • ferrel hunt September 2, 201412:37 pm

        Yes. That is exactly what happens. I downloaded the foxconn f22f1p37 update, extracted the .rom to MMTool, went to Cpu Patch/Insert patch data, browsed for your 771 xeon codes (.bin files) clicked “open” then hit apply, then it changes to amd.
        My friend I am corresponding with, in Greece, sent me the same the same foxconn update with xeon codes added with MMtool; I can load his .rom file and add whatever I want.
        He is helping me do my 771 mods, but would like to learn for myself.
        Thank you much for your quick response.


      • ferrel hunt September 4, 20148:51 am

        I found old version 3.19 of MMTool. It works!


        • syn September 4, 201412:15 pm

          Thanks for the update. I’m glad that fixed it.

  • Anton September 26, 20142:18 am

    what if I’m having bios in .Exe format that I can’t unzip?
    But I’m also having file named A7345IMS.1C0 <– maybe I need this one?

    Motherboard is MSI P35 Platinum (MS-7345)
    Bios version 1.C0 (

    • syn September 26, 20141:34 pm

      I just checked, and A7345IMS.1C0 is your BIOS file, so you don’t need to unzip an .EXE.

  • Anton September 26, 20142:21 am

    And also, what are the microcodes for Xeon L5430?
    It’s CIPID is 1067Ah

    • syn September 26, 20141:36 pm

      The CPUID is actually 1067A (the h at the end just means it’s a hexadecimal number), so you use all the microcode files that start with cpu0001067a_.


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