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

  • Todd March 5, 20184:26 pm

    Any help would be appreciated from anyone who can provide it.

    I am using a very old c2007 Dell XPS 720 (mobo YU822, chipset 680i SLI C55XE Rev-A2).

    I currently have a QX6800 I’m stably overclocking to 3.7GHz on the massive air cooling heatsink that came stock with the system in 2007. However, it will run hot into mid to upper 70s under load (such as when playing Witcher 3) and I don’t want to prematurely burn out the CPU. Inspired by all of this Xeon 771-775 craze, I found a modded X5460 SLANP for like $30 on ebay and figured what the heck. While this CPU was not officially supported by Dell’s latest BIOS version (A06), the Xeon 5460’s TDP, Voltage range, FSB, and C0 stepping are all supported by this mobo/BIOS. This motherboard did not ever have support for E0-stepping CPUs. This motherboard did have official support for some 45nm CPUs as well (Q9450).

    With the Xeon X5460 in place, I am able to post, and boot windows, but will experience random reboots usually within minutes once Windows is running (not overheating according to Coretemp). When I first installed the CPU it ran fine in Windows for about half an hour but Windows hardware added drivers (I assume for the CPU?) and requested a restart….and the random rebooting began occurring after that event.

    I assume there is some CPU feature (SSE 4.1, etc) that the motherboard isn’t utilizing correctly with Windows since it posts and boots Windows most of the time (sometimes it reboots before I hit the Windows desktop). I’ve tried turning off Virtualization, C1E, Speedstep, EPP/SLI, etc within the BIOS and nothing seems to improve the random reboots. The Dell BIOS is limited in what I can mess with (no voltages, etc). I’ve run the system in Safemode which lasts longer but reboots have still happened. When I put the QX6800 back in, everything is great again.

    It is possible the CPU I bought used off Ebay is trash despite supposedly being pulled from a working machine by the seller. However, given that I am putting it into a motherboard that never technically supported it I have to assume the issue is on my component’s end.

    I have tried to modify the most recent Dell XPS 720 BIOS revision (A06) according to the directions on this site.
    I am able to extract the “XPS720-A06.rom” file from the Dell official “XPS720-A06.exe” BIOS update file as directed.
    I am able to combine the two bin-files (cpu00010676_plat00000004_ver0000060f_date20100929 & cpu00010676_plat00000040_ver0000060f_date20100929) for the Xeon X5460 using command prompt.
    However, when I use CBROM195 to add the microcodes to the extracted BIOS ROM file using command prompt, nothing happens. Even when I’m just checking the BIOS ROM with the “cbrom195.exe XPS720-A06.rom /d” command, it just shows the CBROM version info (“cbrom195.exe V1.95 [12/14/07] (C)Phoenix Technologies 2001-2007”).

    I am not sure that I have the PC savvy to mess with a Hex-Editing software. I’m honestly kinda at my limits with what this website has instructed me to do. I am afraid I am going to brick my motherboard and the whole reason I am trying to get this Xeon upgrade is because I don’t have the money for a whole new system right now and I’d like to squeeze a few more ounces of juice from this system until 2019. Xeon CPU seemed like a cheap option for a few extra FPS.

    Sorry for the very long message.


    My system:
    Dell XPS 720 (mobo YU822, chipset 680i C55XE rev A2)
    QX6800 (trying to get X5460 SLANP to work)
    FSB at stock (1066Mhz for QX6800, 1333MHz for the X5460).
    8GB DDR2 Corsair XMS2 PC2-6400 800Mhz (5:5:5:18) EPP RAM.
    MSI GTX 750Ti 2GB OC edition (stock speeds)

    • Stepa March 13, 20187:43 pm

      Utility from Award is not suitable for this Dell BIOS. It seems that in this BIOS the microcodes are written without headers (first 30 bytes). Try using the HEX editor to look for the line “00 00 00 00 A1 00 00 00”, this must be the beginning of the microcode.

      The microcode can be replaced, but I’m not sure if there is a checksum in the bios.

  • hyan March 22, 20188:00 am

    have mobo p5ql pro, really confused between x5470 vs e5450 or x5460 too,is tat extra 0.33 ghz speed really matters? as 5470 is expensive for me. waiting for its price to be reduced,by the way pls tell me 5470 wud reallly make difference from others. i use internet with many pages,play medium games ..mostly counterstrike,watch hd videos,thats all are my usage. thanks,hope i get a convincing reply. :)

  • Greensmack April 15, 20189:50 am


    I suggest you purchase the x5460. I have had one for years in a P5Q Deluxe and it’s worked very well (I am writing from the PC with it). My board allows for overclocking and I have it running a 3.33ghz instead of the 3.17ghz it is rated for. There have been no problems, but I have had a large air CPU cooler for it and am not using a stock cooler.

    I tested using a stock cooler for core 2 duo processors and they won’t work well with a quad core, and work poorly with a Xeon quad core. It will overheat very quickly and would require underclocking the CPU until you installed a better CPU cooler, but it will work enough to get you into your OS.

    • Andrew August 17, 201811:42 am


      well x5460 is 120W CPU and it will produce a lot of heat if you go for overclocking.
      May be you should look at E5450 which is 80W CPU, you will not need massive cooler

      X5460 120W 4346 https://goo.gl/Lt3cSr
      E5450 80W 4210 https://goo.gl/HS2yop


  • oki May 2, 20189:46 am

    well, i have a biostar tpower i45, p45 chipset.
    unfortunately my bios has .bsp extension.
    so mmtools cannot recognize it.
    Can i just rename the bios to .rom and patch it?

    • taz May 2, 201811:01 am

      Yeah, try that. If the patching tool doesn’t complain, it should be fine.

      • oki May 3, 20184:02 am

        okay, thanks.
        It’s now works flawlessly.

        Running e5430 oc to 3.2Ghz fsb at 400.

        As fast as qx9770..

        Quadcore for ghetto..:lol:

  • vinod May 18, 20182:06 am

    I bought a asus p5g41t-mlx motherboard and I have done the bios update with the micro-codes, but after i power up the mobo with my xeon processor(which is modded), it stays a for about 20 secs and switch off automatically and I managed to go to bios,( the cmos ratio value shows MIN 6 – MAX 9……but the actual ratio value indicates 6) …. What should I do?, is there any changes to be done with the cmos ratio/ values? Please help
    My specs are – ASUS P5G41t-mlx
    Xeon e5450
    2GB DDR3
    palit 750 ti dual

  • Yan May 31, 20184:37 pm

    hi guys,
    I currently have a dell inspiron 530 running on a foxconn G33M02 motherboard with the latest bios version (1.0.18) from dell website. I would like to replace the current cpu (core 2 duo E4500) for my Xeon x5460. I need to insert the microcode in the bios but i dont know how to do it.
    Is there a simple guide that i can stick up too ? i’ve been looking on Google but so many forums saying different things.

    • Yan May 31, 20184:39 pm

      also, i know the xeon x5460 is a LGA771 and my motherbaord is lga775, but mod as been made on the cpu to fits lga775.

      • Stepa June 14, 201812:03 am

        Does this motherboard work with TDP 120W processors?

  • Ильшат June 27, 20188:14 am

    Здравствуйте,нужна ваша помощь.
    Мат.плата P5K установлен проц.Xeon L5420.Температура проца очень высокая (80 град).Прошивал биос с офиц. сайта и 2 прошивки (P5K-1201,P5K-1201 anci) пробовал не помогло . Температура такая же. при включении выдает ошибку Cpu Fan Error.(Кулер башня,подключен правильно)
    Что можно сделать ?

    • Андрей August 17, 201811:48 am


      можеш попробовать уже модифицированный BIOS со следующего вебсайта


      Xeon L5420 разработан для низкого потребления энергии и не должен сильно греться.

      Внимание — проверь температуру как ее считывает сам BIOS (Windows программа может не правильно считывать температуру).


    • А August 17, 201811:54 am


      информация на твой процессор L5420


      Смотри секцию ‘Advanced Technologies’ и сверяй с установками BIOS — если процессор что-то не поддерживает, то в BIOS будет необходимо выключить данную установку.


  • Esteban July 2, 201810:02 am

    I have an MSI P35 Platinum and a xeon x5460 I need a modified bios I tried with a bios I found here but it doesn’t give me video I don’t know why

  • KIK July 15, 20188:44 am

    so, i have asrock g31m-vs and in the website itself says that bios dont have another update, which only 1.00 or first released version. i wonder if i could do some modding without updating the bios and adding microcode is it possible?, beacuse the microcode i had was 1067a/a07 on core 2 duo e8400.

    i need help to consider wether should i update my bios with the same version or just do plug n play.

    any reply id appriciated it.

  • horanos007 July 23, 20181:08 am

    1:cpu estok intel xeon x5492 or5472or5470 and minbord asus p5 ql pro or p5kpl mix mode


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