LGA 771 to 775 Adapter (MOD) – Run faster Xeon CPUs in a Core 2 Quad motherboard



Motherboard Compatibility

There are two requirements that your motherboard must meet in order to be able to run LGA 771 Xeon processors:

  1. You must have an LGA 775 motherboard with a compatible chipset.
  2. Your bios must support an LGA 775 CPU that's similar to the Xeon you want to run.

We'll explain how to verify these things in the sections below. And later in this guide, there's also a list of motherboards that have been tested with this MOD.

First, make sure your motherboard's chipset is compatible

The chipset we're talking about here is technically called the Northbridge chipset. You can usually find what chipset your motherboard has by looking at its specification list.

Chipset compatibility table

Note: For known compatibility issues and more details, please see the bullet points (which are shown right after the table).

Xeons that are compatible with each chipset
Chipset5xxx Series3xxx Series45nm65nm
P45, P43, P35, P31, P965
G45, G43, G41, G35, G33, G31
nForce 790i, 780i, 740i, 630i
GeForce 9400, 9300
Q45, Q43, Q35, Q33
X48, X38
nForce 680i and 650iYesYesMaybe
(see below)

If you don't need more details about the topics shown above, you can skip ahead to the next section: Next, make sure your BIOS supports a similar LGA 775 CPU.

What do 5xxx series and 3xxx series mean?

By 5xxx series we mean any Xeon whose model number ends in 5xxx (this includes all the E5xxx, X5xxx, and L5xxx processors).

Issues with Intel brand motherboards

Note: This information only applies to motherboards actually manufactured by Intel. We haven't heard of any problems with ASUS, Gigabyte, MSI, or any other brands.

Some motherboards made by Intel don't work with this mod

For some reason, some Intel brand motherboards that have a compatible chipset and support a similar LGA 775 processor do not work with this mod (please see the list of tested motherboards for the model numbers).

It may not be possible to update the CPU microcode on an Intel brand motherboard

This is sometimes needed to install Windows 8.1 64-bit or to enable all of the CPU features (like Speedstep, SSE 4.1, or VT-X). The older non-E0 stepping processors often don't need a microcode update to enable these features, so if you do try it, buy one of those.

The reason this may not be possible is because Intel has their own proprietary BIOS that nobody currently knows how to MOD (even by manually hex editing the BIOS).

Nvidia's nForce 680i and 650i chipsets don't officially support 45nm quad core processors

Some motherboards with these chipsets have worked with 45nm quad core Xeons, and some haven't (please see the list of tested motherboards for more details). This is likely due to some motherboards unofficially supporting 45nm quad core processors.

My chipset isn't listed here. Will this work for my motherboard?

The mod will still likely work if your BIOS supports a similar LGA 775 processor.

If you do try it, please let us know how it goes by leaving a comment at the bottom of this page.

Our guess as to why some chipsets don't support the 5xxx series Xeons (but do support the 3xxx series)

Xeons with model numbers that end in 5xxx are allowed to be used in motherboards that support 1 or 2 physical processors (this is called dual-processor support). However, the 3xxx series Xeons cannot be used in a multi-processor system (they're labeled as supporting uni-processor configurations only).

The E0 stepping E5440 and X3363 Xeons both have the same CPUID (1067A), which means they're both made from the same silicon and are basically the same internally. Additionally, there's no noticeable difference between them (other than one has dual-processor support), so it looks like this could be causing the problem. Some chipsets may be checking for this and may be blocking the system from booting.

Next, make sure your BIOS supports a similar LGA 775 CPU

Important: Make sure you only buy Xeon processors with a FSB and TDP supported by your motherboard.

How the compatibility table shown below works

Hopefully the table shown below is pretty self explanatory, but here's an explanation if it isn't. Each row shows an LGA 775 processor in the 1st column. If your motherboard and BIOS support that processor, you can run the LGA 771 Xeons shown in the second column (if your chipset supports it).

You should only buy Xeons with a FSB and TDP less than or equal to the values shown (unless your motherboard supports higher).

If your motherboard and BIOS support the following CPU:You can run these Xeons (if supported by chipset):Max FSB
(unless motherboard supports higher)
(unless motherboard supports higher)
Core 2 Quad Q9650Any 45nm quad core Xeon133395WView Xeons
Core 2 Quad Q9550SAny 45nm quad core Xeon with a TDP of 65 W or lower133365WView Xeons
Core 2 Quad Q6700Any 65nm quad core Xeon106695WView Xeons
Core 2 Duo E8600Any 45nm dual core Xeon133365WView Xeons
Core 2 Duo E6850Any 65nm dual core Xeon133365WView Xeons

For a list of all the compatible Xeons, their features, and current prices, visit this page.

If you don't need more details about the topics shown above, you can skip ahead to the next section: Recommended LGA 771 Xeon processors.

Some Xeons have a higher FSB or TDP* than their similar LGA 775 CPU

* TDP is a measure of how much heat your processor's cooling system will have to handle.

Because of this, you need to make sure your motherboard supports the FSB and TDP of the Xeon you're buying. Some motherboards will not boot processors with a TDP over 95W (or 65W for low power boards).

TDPs for some common Xeon processors
  • L54xx series has a max TDP of 50W
  • E54xx series has a max TDP of 80W
  • X54xx series with a 1333 FSB has a max TDP of 120W
  • X54x2 series with a 1600 FSB has a max TDP of 150W

How to check what TDP your motherboard supports

Our list of tested motherboards (shown later in this guide) has max TDP numbers for many motherboards, so you should check there first.

If your motherboard isn't in our list, a good way to check if your motherboard supports 120W and above processors is to check its CPU support list. If your system supports overclocking or extreme edition processors (like the 130W QX9650), you should be able to run the 120W X54xx series Xeons (the 150W ones will also probably work). However, if your system only supports the 95W Q6600 with a G0 stepping (and not the 105W B3 stepping), your system may only support 95W and lower processors.

If you aren't sure what TDP your motherboard supports, I'd recommend going with the 95W and lower Xeons only.

How to check what LGA 775 processors your motherboard supports

If you're unsure what LGA 775 processors your motherboard supports, please read the following article: How to Check if Your Motherboard Supports a Specific Processor.

Be careful if you have a prebuilt system (like a Dell)

Prebuilt computers (like Dell) sometimes use different motherboards (depending on what parts come with the system), and the motherboards may not support the same processors, so you'll need to figure out which motherboard you have.

You should be able to find the model number with CPU-Z.

Right now, the following 45nm Harpertown Xeons with a 1333 FSB seem to be the best deals. These are quad core and have high multipliers (ratios), which means they should also overclock easily.

For more prices and detailed specs on all of the Xeons, visit this page.

2,046 Responses

  • Rob May 17, 20188:57 am

    Hello, I have a question. I have a motherboard (ASUS P5KPL-VM, which has G31/ICH7 chip), then … what would happen if I install the Xeon X5470 ?. The maximum of TDP. of this motherboard is 130W., I wonder if I install that processor on this board.

    Could it get to overheat ?

    Could the board die? or

    Would it need better refrigeration?

    I’ve also been seeing that it has 3 vrm phases without a heatsink, I do not know if that can cause something in the heating up.

    Or directly move from this board and upgrade to a more current system like the 8th Generation of Intel?
    Thank you.

  • vinod May 18, 20181:08 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 e5450 (which is modded), it stays a for about 20 secs and switch off automatically…. 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

    • kjafkjkaf May 20, 20182:45 am

      change the cpu fan it turns off cause of overheat

  • tom May 18, 20189:56 pm


    I have a Q9550 and I would like to make a mini-itx HTPC. The best mobo that I can find is the Intel DG45FC.

    Some reputable websites say this CPU and mobo are compatible, yet, others say they are not compatible.

    Please help!!! Will the Q9550 work with the DG45FC?


  • Kevin May 25, 201811:25 pm

    Hello i had some problem that my xeon is too damn slow the xeon even cant load windows in 4hours.

    But i do few tricks that i install windows on my pentium dual core and then i replaced to xeon procesor. ZThe boot works but take around 10minute to go to the desktop, and the cpu load is soo danm high, cursor stuter (even its fresh install) .if im going to reinstall windows with xeon processir it will freeze. ( in this trick if i go to safe mode, the xeon worked fine without any problem)

    Hope you can solve my problem

    I cant install windows 7 with xeon l5420, the installation takes forever so i do it with my dual core and swap the processor to xeon.

  • john789 June 1, 20189:53 pm

    I am very interested in doing this, as I didn’t even know that it was even possible, but I need some help.

    Here goes:

    My motherboard is a Gigabyte GA-P35-DS3L version 2.0 with 4 sticks of PC2-6400 2GB 2X1GB DDR2-800 for 4Gb of ram and a E2160 cpu overclock to 3.0 ghz. I checked the motherboard compatibility list and my mb is approved.

    I read the article here https://www.delidded.com/lga-771-to-775-adapter/

    But I still have a few questions, do I need to mod the bios to Update CPU Microcode in an Award BIOS? If so, I would like the keep the microcode for the E2160.

    I would like to get either the E5450 or the E5430.

    Also can you tell me what bios settings I need to make in the bios for this to work?

    Thank you.

  • Zach June 1, 201811:29 pm

    Confirmed this mod works on a Foxconn g41s-k motherboard with a L5420 Xeon. This Motherboard has a Max tdp rating of 65watts. Its not just plug and play though you will have to install a modded bios to bypass the CPU Max tdp warning screen. I was fortunate to have found one with the proper microcodes added as well.

    here is the link.

    This mod should also work on the g41s motherboard as well.

  • dev893 June 3, 201812:20 am

    So I have the CPU installed and first boot it works fine then if I reboot for any reason it freezes on the windows 10 boot screen, I’ve got the updated BIOS with microcodes, I modded the socket and added a sticker to the CPU I had to put the C2D e8400 back in, is it possible it’s a bad CPU?

  • Andrew June 6, 20186:58 pm


    I have P5B-MX mainboard which supports upto Q6600 Core 2 Quad CPU.

    I’ve got Xeon E5405 CPU (4 Cores 12MB cache, 2GHz, 1333 MHz FSB, 80W) for BIOS modification

    0. attached LGA 771 to LGA 775 adaptor to the CPU
    1. downloaded P5B-MX BIOS ROM file
    2. deleted support of Intel D and Intel 4 CPUs microcode
    3. injected suggested microcode for CPUIDs 1067a/10676/10677
    4. programmed P5B-MX mainboard with resulting BIOS
    5. attempted to boot the computer with Xeon E5405 and boot failed

    Did I make any mistake? Is there a reason why P5B-MX refuses to boot with Xenon E5405?
    NOTE: P5B-MX, FSB 533/800/1066(o.c)MHz, THD 130W

    I have put original E2200 CPU back in P5B-MX mainboard and the computer boots fine.

    Modified Xeon E5405 works fine in HP Vostro 220s computer without any issues (run Knoppix for a day).

    Thank you,

  • Sushil June 20, 20185:44 am

    I have ASUS P5G41C-M LX motherboard which booted perfectly fine with Xeon x5450 with the help of this mod.Before adding the cpuid patches, i was able to boot up the system with windows 7 but the system didn’t boot with Windows 10 x64 bit. After using the modded bios the system is working perfectly fine so far.I have also added Dell Slic 2.1 for Windows 7,so i just hope it would be useful for someone else.

    ASUS P5G41C-M LX Modded Bios:https://drive.google.com/file/d/1pX41QZvNR7ITQzIudbzmf8QgOdi7AKue/view?usp=sharing

  • sprit June 21, 201812:55 pm

    i have a asrock g41c-gs r2.0 will a x5460 work on my motherboard if i already have a q9400


Leave a Comment

Problem with this MOD? Please read the troubleshooting section before reporting a problem. If that doesn't help, please tell us all of the things you've already tried.

Unsure about compatibility? Please read the motherboard compatibility and tested motherboards sections of this guide.