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



If you're looking to extend the life of your LGA 775 system, there's an adapter available now that will let you install faster (and usually cheaper) Intel Xeon processors (LGA 771) into a Core 2 Quad motherboard (LGA 775). These Xeons cost a lot less and are basically identical internally to the high-end Core 2 Quad CPUs.

List of LGA 771 & 775 CPUs + Current Prices

The pages shown below should help with comparing Xeon prices and specifications. The first link has all the LGA 771 and LGA 775 CPUs combined into 1 table (sorted by price), and the others are the original uncombined pages.

Where can I get an adapter?

Here's a current list of sellers (sorted by price). The sellers are located all over the world, so you should be able to find one that's close to you, and most of them will also ship worldwide.

Why would you want to do this?

Xeons are usually MUCH cheaper

For example, the Xeon E5450 is equivalent to a 3.0 GHz Core 2 Quad Q9650, and it currently costs about $15 (about $70 less than the Q9650).

Other good deals on LGA 771 Xeons include:

For detailed specs on all of the Xeons and a full list of current prices, take a look at this page.

Xeons also typically overclock better

Additionally, if you’re interested in overclocking (making the cpu go faster than its default speed), Xeon processors are usually made from the best silicon, so you can typically achieve higher overclocks with them.

Someone that recently did this mod successfully overclocked a Xeon X5470 from 3.33 GHz to 4.5 GHz on an ASUS P5Q PRO motherboard, so you can achieve really good results with these Xeons.

How does the adapter work?

The adapter is basically an electronic circuit on a sticker, and you place it on the Xeon processor (as shown in the picture below). This switches two of the pads on the bottom of the Xeon to make it compatible with a Core 2 Quad motherboard.

Xeons that are compatible with this adapter

This adapter is only compatible with LGA 771 Xeon processors. If you're unsure what LGA 771 means, it's the name of the CPU socket used in some Xeon motherboards. And in comparison, LGA 775 is the name of the socket used in Core 2 Duo/Quad motherboards.

LGA 771 to 775 Adapter

Minor modification to the LGA 775 socket is also required

If you look at the LGA 775 socket in the picture below, you'll notice two tabs are circled in red. These tabs are there to stop you from installing a non-LGA 775 processor, and they'll need to be fully removed before you can install an LGA 771 cpu.

The tabs are pretty easy to remove if you have a sharp utility knife or box cutter (just be careful not to damage or bend any of the socket pins near the tabs).

Important: Make sure that you fully cut off each of these tabs. If they're not fully cut off, the processor may not align or seat correctly in the socket, which will stop it from making contact with all of the pins. If this happens, your system will likely fail to boot.

Once the tabs are cut off, you can use tweezers to safely remove the pieces from the socket.

The socket will then support LGA 771 or 775 processors (you can still reinstall your old processor if you ever need to).

Tabs to removed from the LGA 775 socket

1,619 Responses

  • DannyMinh March 24, 201712:23 am

    Anyone success with Radeon Xpress 200? I did the bios mod (remove Celeron/ Pentium 4 microcodes) to the latest HP bios of HP Pavilion g2075l Desktop PC (mainboard ECS RC415ST-HM) to work well with Core2Duo E6600 (at 2.4/1066 and VT enable). Will it run 45nm Xeon if I further mod bios to remove all Pentium D microcode?

  • Detonalta March 25, 20177:45 pm

    Hello, I bought xeon x5460 and I have a POS-ECSG41BS that so far I have not found the bios driver, can you help me?

  • West View March 27, 201712:03 pm

    Thanks for the informative website. I replaced an E7200 with an L5430 for a media server/NAS. Minor issues with the motherboard BIOS: it recognized the Xeon, however, the microcode was incomplete and did not indicate the cpu supported the CompareExchange128 instruction (among other things [SSE 4.1], so Windows 10 64 bit would not install. Flashing the BIOS with the latest Intel microcode from your site fixed the problem. I’ve seen other people complain about issues getting Windows 10 to run on Xeons, and likely this is the problem: an incomplete implementation of the Xeon microcodes in the BIOS. It is interesting that programs like CPUID and Coreinfo only read what the BIOS tells them about the CPU and are not finding details from the CPU itself. Thanks again for all the instruction and information!

  • Thiago March 27, 20176:21 pm

    I bought a Xeon E5440 and it’s not working properly with my Asus P5N-D. May you help me please?
    I’ve been getting restarts every single time when the “starting windows” screen appears. So i noticed that when i lower the FSB from 333 to 315, the system works, even though the computer is slow…
    My configuration:
    Xeon E5440
    Asus P5N-D nForce 750i chipset
    2x2GB DDR2 800MHz
    Corsair CX430 PSU
    Thanks in advance!

  • db2x4 March 27, 20177:44 pm

    xeon 771 mods on stock bios.

    -Lenovo ThinkCentre M57e 9356/9487 G31 (G31T-LN, G31T-LM)

    Xeon E5440, X5450, X3363 work great at first start power on with stock latest bios without show any error message on post

    but speed is reduce can’t set the clock multiplier inside bios and need to add some microcode to show more instuctions on CPUID app.

    look like this mobo can support the 65nm clovertown xeon too after try the old 65nm celeron 420 the same architecture is work. I’ll test later when the x5355 arrive to me.

    -Lenovo ThinkCentre M57 Q35 (6068)

    X3363 work great at first start power on with stock latest bios but show error message “0167: no processor bios update found” on post and booting to windows.

    the system automatically run with full speed and we can set the clock multiplier inside bios and need to add some microcode to show more instuctions on CPUID app.

    xeon 5400 harpertown series -confirm not working


    -dell optiple 755DT Q35

    X3363 work great at first start power on with stock latest bios (022)

    the system automatically run with full speed and show all support instructions on CPUID app.

    xeon 5400 harpertown series -confirm not working


  • iscsi March 28, 20178:07 am

    Hi, All

    Intel DP43BF latest bios 088 working with E5450 C0 (SLANQ)/Windows 10 like a charm w/o any hacks.


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.