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

  • kymera November 5, 20149:38 am


    I have a Foxconn G31MX-K motherboard.
    I downloaded the latest bios version ( 773F1P12 , from here: )
    I unzipped the fille.
    I renamed the bin file to 773F1P12.ROM but the MMTOOL V3.26 can’t open the file. Error message: Error Loading ROM Image (10003H)

    Please help .


  • gabe November 6, 20146:58 am

    hi all ….
    I have a ASUS P5Q Turbo & xeon e5440 and the last update from asus ASUS P5Q TURBO 0602 , I ‘ve tried to add the microcode using MMTOOL .
    I added -cpu0001067a_plat00000011_ver00000a0b_date20100928

    and remove only one cpu id that I found using the same 067A .

    I actually dont know if this the right way …. ?
    for example , after I mod this bios there still a change I can use my Q8400 ?


    • syn November 6, 20141:39 pm

      That’s right if you have an E0 stepping CPU.

      Yes, you can still use a Q8400 after updating the microcode because the method used in the guide also updates the LGA 775 microcode.

  • James November 19, 20147:37 am

    Hi syn,

    Not entirely on topic, but could you tell me where can I acquire the microcodes (for AMI) but for s.1155 and s.1156?

    Thank you.

    • syn November 19, 20148:59 am

      Hey, James. The microcodes are available in Intel’s download center:

      You can extract the microcodes with a program called microdecode.exe.

      • James November 19, 20149:34 am

        syn, you’re simply THE best!

        Used the said tool and got slew of .bin files. Any help cherry-picking the 1155 & 1156 files?
        Don’t really know how to go about it.

        • syn November 19, 20145:46 pm

          You should set aside all the microcodes that have a CPUID used by 1155 and 1156 processors. You can figure out which CPUIDs these processors use by looking at this list: The “Processor Signature” column is the beginning of the CPUID for that processor.

          You’ll also probably need different software to mod the BIOSes because the BIOS has changed a lot since these LGA 775 processors. I haven’t modded newer BIOSes, but I’d try searching for newer versions of these programs.

          Here’s a modding tool for newer AMI BIOSes:

          Good luck.

          • James November 24, 20144:22 pm

            Hi Syn, reporting on my task.

            I was slightly confused at the beginning, but I successfully flashed a Lenovo M71e machine with an Intel H61 chip (which supports IvyBridge) but Lenovo decided not allow customers to place 3rd gen CPUs, Sandy B only.

            Well, the joke is on them. Added the microcodes, flashed the bios and those Ivy Bridge puppies starting running like you wouldn’t believe. Did it with a higher version of MMTOOL. The one in your link did not permit the rom files to be properly opened.

            Never knew modding BIOS could be SO darn helpful!

            MANY thanks!

  • James November 19, 20149:39 am

    And more on topic:

    I was able to microupdate and install (following your tutorial) an Xeon L5430 to a Lenovo A70 / G41 DDR3 system.
    In fact, I updated the microcodes to enable Quad 775 CPUs as this chip supports it but is listed by Lenovo as only supporting E8600 max.

    Again, thanks to your work here!

  • John Peacock December 21, 201410:32 pm

    I’m building a BIOS for an Asus Maximus II Formula. SLANZ is the CPUID of the X5482 I want to install in it. Is “cpu0001067a_plat00000044_ver00000a0b_date20100928” the file I want to update from in MMTool? The CPUID comes back on CPU-World as 1067ah is why I ask. Thanks.

    • syn December 21, 201410:45 pm

      Yeah, that’s the right microcode. The ‘h’ in the CPUID just means it’s a hexadecimal number, but it isn’t part of the CPUID. I’m not sure why they include that.

  • Merica January 6, 20154:09 am

    I just ordered a Xeon L5430 and planning to put it into an HP DC7800 Ultra Slim Desktop. The USDT is currently running an E6300 Core 2 Duo 1.86ghz cpu with a TDP of 65watts and I thought the motherboard is sporting a Q35 Intel chipset. I’ve downloaded your microcode and MMTool and have already the two files needed set aside, but my question is, since it’s Hewlet Packard/Intel BIOS, how do I come about installing a microcode on an HP machine? Oh, btw I don’t need to modify the motherboard since the Xeon L5430 has already been precisely milled to fit an LGA 775 mobo. Thanks for your help.

    • syn January 6, 20154:18 am

      I hate to tell you this, but the L5430 probably won’t be compatible with your motherboard, since it has a Q35 chipset. The Q35 chipset usually doesn’t suppoort 5xxx model Xeons. This is explained more in the motherboard compatibility section of this guide.

      Updating the microcode probably won’t help in your case, but everything I know about updating the microcode is explained in this guide:

  • pluvinel January 27, 201511:14 am

    Congratulation for your job. Very well done…
    I have installed a Xeon X5482 in a Asus P5K. It works perfectly.
    I got a P5Q SE to have the P45 and ICH 10 chipsets. Unfortunatly I did a mistake. I have installed the processor in a wrong position in the socket…. Of course it does not work. I have try with the processor in normal position but I cannot have acces to the bios. All seams OK, the system starts, the fans turn etc but I have a black screen. I did some tests with other 775 processors seval memory etc Nothing. The socket is physicallly ok and the X5482 works apain in my P5K…
    I premuse it is not the first time it happens. Do yoy have some suggestion to do ? My mainboard is brand new…
    Thanks in advance for your help

    • syn January 27, 201512:31 pm

      Just to make sure I’m understanding you correctly, you tried another regular LGA 775 cpu in the motherboard, and it also didn’t work? I’m not sure what damage can be done by installing the processor in the wrong position, but it does sound like it probably fried something. The only fix I know of is if there were bent pins or something in the socket, but if the socket looks good, I’m not sure what else to try other than fully resetting the BIOS.

  • pluvinel January 27, 20151:15 pm

    Hi, Thanks for your quick answer.
    The 771 and 775 processor are a square and it is possible to turn them in all postions when the tabs are removed. Its fit perfectly in the socket. I have check, no pin bent. After my mistake I have turn the processor in the right position and I have try two other working processors 775. Same trouble. The motherboard starts normally and can stay like this with a black scren before the bios. The processor 771 I have baddly installed works perfectly in my otheir motherboard and is not dommaged. Excepted to try several componants I have nothing else to test the motherboad and as I am short with money if I send it to repare it coasts me two times the price of the card…
    I have not try to do a clear cmos but as I cannot reach the bios I’m not shure it changes somthing.
    Do you have other idea ?
    Thanks a lot
    Best regards

    • syn January 29, 20159:22 am

      You can clear the CMOS through the jumper on the motherboard or by removing the CMOS battery (it looks like a watch battery).

      For more details, check out the link below:

      • pluvinel January 29, 201511:27 am

        I have clear the CMOS and… IT WORKS !!! I was sure to have burned out the masterboard…
        Thank you very much for your advise.
        Best regards

        • pluvinel February 1, 20157:21 pm

          New trouble…
          I have used my X5482 on my new Asus P5q SE plus during several hours. It works normally.
          To update a software I boot the system and I got a Win 8.1 message : your computer… impossible to read more it stays 1/10 of second but after that the system boots but no bios… I try several starts, nothing happens, the fans turn etc but no bios and blank screen.
          Clear CMOS, I got the bios and same situation impossible to start the OS and at the next start no more bios…
          I remove the X5482 and I put my Q9300. Clear CMOS and the system starts directly… I used the computer for a while. It works. I come back to the X5482. Clear CMOS, start, I have two short bip, once I have the bios but no start and again boot no bios etc and always the two short bip…
          My configuration :
          Asus P5Q SE PLUS. Last bios with and without last microcodes for 771 and 775 socket, Intel X5482, Intel Q9300, Corsair memory 6400 and 8500 tested on several socket.
          I have read several time all your advices and I have tried several option and configurations, check every things… No pin bent, adaptor 771/775 in the right position…
          Now I don’t know what to try.
          I need your help…
          Tank’s in advance

        • syn February 1, 20158:17 pm

          I’m not sure if I fully understand what you said. So you used the X5482 on your P5Q SE plus motherboard for several hours, and it worked fine. Then you went to boot it one time, and you got the error message? Did you install some software or change something? Was this the first time you rebooted the system since you installed the Xeon?

          If I had to guess with what I know at this point, I’d say the microcode may not have been updated correctly. Did you remove all of the old microcode that had your processor’s CPUID?

          Did you go into the bios (after resetting the BIOS through the jumper) and load the default settings? That is also sometimes needed.

          If that doesn’t help, you may want to also try mentioning this problem here: They may be able to respond quicker than I can. They also know a lot about the mod.

          • pluvinel February 2, 20156:01 pm

            Tank’s for your answer.
            The situation is : I used a X5482 on Asus P5k since several months. It works fine. I got a brand new P5Q SE+ and I have installed all my components on it in my computer. I did a mistake, as you know, I have turned the processor of 180 °. That is why I came to you. You gave me the solution: clear the CMOS. After to do that I have used my computer few hours normally and when I restart it after an update of software I got a message saying that my computer have a problem (win 8.1 message) auto start but no more bios… To have the bios I must clear the CMOS, F1 setup save and exit and after that auto start and no more bios again etc… I have tried all possibility. The OS work, I have tested it again on my P5k with the X5482. No trouble on it… I have tried the last bios (it accepts the QX9770 very similar of the X5482) without and with the last microcodes 1067A for both 775 and 771 socket. The old one was deleted… All the components work on the P5K and were working on the P5Q SE+ for a while and work on it with the X9300…
            The trouble comes only when I put the X5482 and P5QSE+ together…
            What I don’t understand it is why after the clear XMOS I have the bios I configure it and I loose it at the boot and I must make again a clear CMOS…
            Can you suggest me something to try ??
            Best regards

        • syn February 3, 20152:16 pm

          The only other thing I can think to try is reinstalling windows. I know this issue causes you to not see the bios, so you may think it’s not OS related, but Windows does update cpu microcode on bootup (and maybe other bios related stuff), so it could be causing some issue that requires a bios reset to fix.

          That’s probably what I’d try.

          • pluvinel February 3, 20153:55 pm

            Thank you again for your help.
            I have two sata 3 hard discs on my computer. One with XP sp3 in IDE, the other Win 8.1 in AHCI. The Os work perfectly with the Q9300 on my P5Q SE+ and P5k with X5482…
            What ever the combination I have or without HD, I meet the seam trouble when the X5482 is on the P5Q SE+ . I have try to do directly F2 with just the IDE disc connected but after the boot I loose the bios…Each time I have the bios after a reset CMOS when the system boot again I loose it…
            What can make that… ? It is may just a stupid thing…
            If you have an idea… I try on my side to find somewhere a solution.
            Thank you

        • syn February 3, 20155:15 pm

          I remember 1 other person having this problem (it’s in the lga-771-to-775-adapter comments somewhere), but I can’t remember if or how we fixed it. I would have written it in the troubleshooting section if the solution was something I hadn’t heard before.

          After a BIOS reset, the system looks at all of your hardware and stores some info in the BIOS. It must be storing the wrong value for something that’s causing it to not boot the next time.

          I remember 1 person saying their ram timings, ram speed, or ram voltage was getting set to the wrong values. When they manually set these values, the system worked fine, so you may want to check that. I don’t think they had this problem without a Xeon.

          If that doesn’t help, try reducing the speed of the X5482 in the BIOS (either lower the cpu multiplier/ratio or the fsb speed). Your system may not be stable when it’s running at full speed for some reason.

          Next I’d try removing all unneeded hardware in your system (use 1 ram stick, remove any addin cards, extra hard drives, dvd) just to make sure one of them isn’t causing problems with the Xeon.

          If you upload your modified BIOS, I’d like to take a look at it to make sure the microcode was added correctly.

          • pluvinel February 4, 20158:42 pm

            Thank you for the time you spend to help me.
            I have installed again the X5482 and proceed to new tests with just 1 HD, 1 ram stick, the graphic card and a new bios with the last microcodes.
            I have tried several memories 6400 and 8500 on each socket. I have set manually the value of the ram Corsair dominator 8500 (frequency, timing, voltage). I have not modified the value of the CPU, FSB (1600 for the X5482) They are on auto. I don’t know what to do here. The cpu frequency and tension depend of the charge of the system.
            Always the same reaction. I set the bios, the system boot and blank screen. It is probably something stupid causing the trouble but which one? (FSB and CPU frequency synchronisation ?).
            You have a copy of the bios used if you find something wrong…
            Thank you again for your help
            Best regards

        • syn February 4, 20158:58 pm

          Try changing the FSB to 333 (yes 333 not 1333). That number gets multiplied by 4 to make the actual FSB. 333 * 4 = 1333 instead of 1600. That should also automatically reduce your CPU speed and ram speed.

          • pluvinel February 5, 20157:56 pm


            I will try to change the fsb value but the idéa is to have a faster processor not to use it at low speed…
            How can I send you a copy of my bios file. From my mail I got a failure notification and here I don’t know how to do ?
            Best regards

        • syn February 5, 20158:15 pm

          The point in lowering the FSB is to see if it fixes your problem. If it does, the processor or motherboard isn’t capable of running it at full speed.

          You can upload files to, and then post the link here if you want.

          • pluvinel February 10, 201511:13 am

            I come back on my trouble.
            Since several days I use the P5QSE+ with the Q9300. I have overclocked it to 3000 Hz and it works perfectly but I have always for idea to use my X5482…
            The thing I don’t understand is why the P5QSE+ and the X5482 had worked together for a wile and not now knowing that each component is ok, all of them on my P5QSE+ with the Q9300 and with the X5482 on my P5K ?
            Why after a clear cmos I have the bios and after the setting and the boot I got a blank screen without error message and why I am obliged the make a new clear cmos to have again the bios like something has corrupted the bios during setting?
            It is not a problem of OS I have try two HD with Windows 8.1 and on other with XP working.
            I don’t know what to try…
            Here you have the links to the bios file I use and the report of benchmarks of my P5QSE+ when it was working with the X5482. I it can help to find something.
            Thank you for your help.
            Best regards

          • pluvinel February 10, 20155:38 pm

            Thank you
            Yes the EO is ok for my processor. Anyway my motherboard has run with this bios and the W5482. It accepts the qx9770 with fsb 1600. Do you have an idea why it does not work now and why the bios disappears after a boot ?
            Best regards

        • syn February 10, 20152:03 pm

          It looks like you updated the microcode correctly for CPUID 1067A.

          Are you positive you have the E0 stepping of the X5482? There’s also a C0 stepping of that processor.

          If you tried lowering the FSB as I mentioned earlier and it didn’t help, I really don’t know anything else to try at this point. I’ll let you know if I think of anything else.

          • pluvinel February 11, 20155:12 pm

            I have tried once again to use my X5482 on the P5QSE+ but at the blank screen instead to do a clear cmos I have restarted several times and after 4 or 5 boots the system starts and it works normally now !!!
            Thank you for the time you spend to help me
            Best regards

        • syn February 11, 20155:22 pm

          Thanks for the update. I’ll add your problem to the troubleshooting guide. It will probably help someone else that runs into the same issue.

  • Geo February 10, 20156:28 pm

    Step four where do find your bios?

    • syn February 10, 20156:52 pm

      Try searching for your motherboard’s model number along with the keyword BIOS on Google.

  • Diaz Bordeaux February 16, 20158:08 am

    Hi all Modding-Practitioner !

    I have a ASUS P5E Deluxe with the original bios Rev 0405. This mainboard run fin with a Q9450S (S-spec SLAWR CPUID 10667). I successfuly updated to the last update bios from asus Rev 0501 with AFUDOS 236.

    A friend of mine run the same board bios 0501 with an LGA775 Xeon X3360 (10676 SLAWZ).

    I decide to buy an LGA771 Xeon X3363 (10676 SLASC) and i do the LGA771-TO-LGA775 Mod with success.

    The mainboard start well but with a warning stating that the bios must be upgraded for this CPU.

    I decide to do the Bios-Modding following step by step your excellent guide :-)

    In MMTOOL, with CPUID 0676 i found only these 2 microcodes :
    ID 0106760C Plateform 01 updateRev 0c date 2008/01/19
    ID 0106760C Plateform 10 updateRev 0c date 2008/01/19
    I delete them and i add the 4 microcodes:
    I save the modded bios in a new file V0501MOD.ROM

    I fail in the flash bios update with all asus tools (EZ flash, AFUDOS 232, 236 and 241).
    the message is ROMID incompatible or Bad boot block…

    In some asus vip forums it is suggested to use engineering version or I tried with no success.

    Thanks for all your suggest…

    Regards from Bordeaux

    • syn February 16, 20153:16 pm

      Yeah, you should be able to flash the bios just the same as you would a normal bios.

      It sounds like you modded the bios right, but I went ahead an modded your bios for you in case there was some problem: I updated all of the 45nm microcodes. Everything went fine, and I verified the codes were added correctly, but please try it at your own risk.

      If that helps, please let me know.


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