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.
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 to Update CPU Microcode in an Award or Phoenix BIOS – For LGA 771 & 775
- How to Update CPU Microcode in an AMI BIOS – For LGA 771 & 775
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
- Contains microcode for all LGA 771 Xeon processors (except older Pentium 4 based 50xx models).
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, or 11
- 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:
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
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.
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 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:
This needs to be done from a DOS command prompt window.
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.