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 $38 (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


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  1. Jordan

    xeon x5450 on dell XPS 720-WORKED NOT STABLE.EXPLORER CRUSHES,WORK ON INTERNET EXPLORER (sometimes crushes),google chrome almost evry time crushes,Tried on another 720 ,doesnt run at all

    • syn Moderator

      Yeah, only 65nm processors seem to run stably on the XPS 720. Someone else tried an X5470 (it’s in the list of tested motherboards).

      The nForce 680 chipset seems to be hit and miss with 45nm quad core cpus.

      • hregg

        I have a x5470 running on MSI P35 Neo-2fr, works fine. Only problem I have is that Ubuntu package cpufrequtils doesn’t support this cpu so I can’t change the cpu scaling governor (a high performance governor will increase power usage, for example, and make the processor more responsive). Besides that, it’s running perfectly.

    • syn Moderator

      If you haven’t already, I recommend trying the stuff in the troubleshooting guide. It’s possible it will help.

  2. Anton

    Ok, installed L5430 on MSI P35 Platinum (with modified bios).
    Works fine, BUT I immediately got temps of 70C for every core.

    I actually use stock Intel cooler for my previous cpu (it was Core2 Duo E7400, it has about 37-39C when idle with that cooler).
    I reinstalled my cooler, re-applied thermal paste, so it’s not an issue with this.
    I’m a bit surprised – that L prefix should mean “Low power consumption”.
    Also, cpu-world says that TDP for this Xeon is 50Watts (http://bit.ly/ZQW2xp), so I thought stock cooler should work.

    I used OpenHardware Montior to monitor the temp.
    For a moment I thought it may read temps incorrectly..
    So I download some other software (RealTemp) and fired it up.
    It indicated the same temperature..

    Ok, immediately when I power up the PC, in bios it shows temps of 37-39.

    So, can anybody explain to me?
    Is this a real issue with cooler and I should get something better?
    Or can it be (because of the mod maybe?) that software tools read temps incorrectly?

    Also, anybody else here faced same issue?


  3. Anton

    UPDATE to the post above.

    Right, I should’ve read troubleshooting guide here before posting.
    So after I installed AIDA, it shows the correct temp.

    That’s right, I figured if my temps were as high as 70C, my cooler would be insanely loud. It’s not.

  4. herewego

    Xeon E5472 didn’t work on Intel DG41RQ (latest bios, didn’t post). Worked fine on Asus P5Q Pro.

  5. Moishe

    Motherboard: Asus P5B VM SE 1.02G
    CPU: Xeon 5430 SLANU

    Works fine. Shows “2.13Ghz” at post eventhough this is a 2.66Ghz CPU, I wonder why, but still good enough for me though.

    Needs a BIOS update or else there’s a CPUID nag at POST, did so myself with MMTOOL and flashed with AFUDOS 2.17 to avoid checksum mismatch error that prevents flashing.

    Other thoughts: Motherboard is ICH8 but does not support AHCI. Added a few more capacitors in the empty spots of the CPU VRM to beef it up.

    • syn Moderator

      The 2.13 GHz speed is probably because the CPU is running at a 1066 FSB speed instead of 1333. If you’re able to overclock the FSB, you can probably fix this.

      Here’s what it says in the cpu support list for your motherboard: “Due to chipset limitation, 1333FSB processors can only run at a maximum speed of 1066FSB on this motherboard.”

      • Moishe

        Thanks Syn.

        I initially thought this had something to do with SpeedStep, but you’re right. This has no official FSB1333 support like the regular P5B.

        Here’s where I stand so far with this. Upon further testing, cores 3 and 4 immediately fail Prime95. The only way to stabilize them is by lowering the FSB and multiplier untill the CPU is running at 1.20Ghz.

        I have another E5430 I want to test it with, and I’ll probably try a different PSU just to rule that out, but this motherboard should most likely be classified as a FAILURE with regards to the mod. Note that this is the P5B-VM SE which is not currently in your list, so AFAIK, I’m the first person to try it.

      • Moishe

        Ok, here’s the definitive word on the P5B-VM SE:

        I tried a different E5430, also SLANU (C0 Stepping), same failure in Prime95 (Expected 0.5 got 0.4). Tried throttling the RAM down to 533MHZ (PC2-4200), same error. Tried a different known good PSU, same error.

        Can’t increase voltage, this motherboard has no voltage adjustment. I have two regular P5B boards to test these E5430s with, just to rule them both out as the problem.

        But it’s safe to say that the P5B-VM SE should be placed on the chart as a FAIL.

        Thank you for all your helpful information.

  6. Charles

    Thanks a lot for this mod. It works perfectely. I have an ASUS P5KC and intall a Xeon X5450 SLASB. It requires to update the Bios, but that’s easy with the mod. Anyway, if it can help, you can use this updated bios tested and validated on my P5KC rev1 motherboard.

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