LGA 771 to 775 Adapter (MOD) – Run Cheap 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 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 Xeon Processors (with current prices)

http://www.delidded.com/list-of-intel-lga-771-xeon-processors/

Where can I get an adapter?

For a current list of sellers (sorted by price), check out this page.

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 $34 (about $90 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

416 comments

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  1. M

    Hi Donnie!

    New MB for the compatibility list: Xeon E5450 SLBBM and ASUS P5QPL-AM.
    BIOS version 0416 modded to add support for Xeons. RAM – 2x2GiB Kingston DDR2 PC-6400.
    Basic and budget friendly motherboard with G41/ICH7 chipset – short review http://forums.anandtech.com/showthread.php?t=319319.

    I bought CPU with adapter attached, so the only difficult part of work was cutting of plastic elements from 775 socket. It’s so small ;-)
    After few days of working with E5450 I found no problems. Testes with Passmark, Prime95 OCCT, few modern games. CPU Mark 4538 without overclocking.

    Thanks for the great collection of info about 771 to 775 mod.

  2. Nick Berrow

    Gigabyte G41M combo V2.0 with FB BIOS (BIOS set to ‘fail safe’ defaults before processor switch). Booted first time with X5450 SLBBE (bought in error instead of E5450 but thought that I would try it anyway).
    I have a bit more heat to get rid of compared with e5450 but see a really good increase in speed of PC with win7 64-bit.
    Great mod!!

    • Nick Berrow

      Gigabyte GA G41M combo V2.0 apparently has max TDP of 135W so Xeon ‘X’ series should not be a problem (max TDP 120w?). In listings you have it down as 95W max!

  3. Phil R.

    Happy to report a relatively painless installation of a SLANP – Intel Xeon X5460 into a MSI P43-C51 mobo. Used MMTOOL to update the BIOS with the correct mircocodes and did the ol’ CMOS clearing. After an initial boot failed to get a post, I simply reseated the Xeon to ensure the sticker was correctly aligned. Booted up fine after that; used MSCONFIG/Task Manager to reset the correct # of cores reported to Windows 7, and after a reboot I’m doing fine. Modest overclocking via FSB bumpups (just ~15% speed increase) have so far gone just fine.

    Many thanks for the thoroughness of your documentation and links. Immensely satisfying to get this mod up and running :)

  4. Dobre Catalin

    New MB for the compatibility list: Xeon X5460 and ASUS P5N73-AM chipset nForce 610i.
    I add the microcode in bios version 0602, because the last one is not recognize by my motherboard.

  5. Roy

    I have some more motherboards with a Xeon working:

    – HP IPIBL-LB works with L5420 E0 and C0
    – Zotac g43itx-a-e works withL5420 E0 and C0
    – Asrock G41M-VS3 R2.0 works with L5420 E0 and C0 (<———-Still for sale and with DDR3! :D)

    ———–I DID REPLACE ALL (!!) THE MICROCODE SO I DON'T KNOW IF IT WORKS OUT-OF-THE-BOX.———–

    I bought a bunch of L5420 on eBay and instead of modifying the socket i machined some extra positioning cuts into the cpu:

    http://tweakers.net/ext/f/TNVQHpdAz2MSoyjH4fPmjQS4/full.jpg
    http://tweakers.net/ext/f/cAUmmkE1dospSyHjVtww5x2R/full.jpg
    http://tweakers.net/ext/f/UEyFP5Iu00uwYEaS7oFBdeH7/full.jpg

    I did not want to risk destroying my motherboard. A Xeon is usually cheaper then a motherboard so i think this is the way to go. My computers use around 45Watts in idle with the L5420 installed (with SSD and NVS295). Still not as good as my Core i5 computer (15Watts) but it only costs 1/5th to build a Xeon pc.

    The above motherboards won't boot above 340FSB so i can't share overclocking results. The HP obviously won't do overclocking at all since it is an OEM board. I'm sure the L5420 will go much faster if you use a decent chipset.

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