GX520 SFF + Pentium D 840 = Incompatible Processor! - General Hardware - Desktop - Dell Community

GX520 SFF + Pentium D 840 = Incompatible Processor!


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GX520 SFF + Pentium D 840 = Incompatible Processor!

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Hi all,

I upgraded my GX520 SFF desktop from a Pentium 4 3.0Ghz HT to a Pentium D 840 (dual core 3.2ghz) processor, but on startup, I get a message about the processor being incompatible and I have to hit F1 to boot the computer

The computer seems to work AOK and is indeed showing correctly via CPUZ/CPUID, as well as in Windows itself, but despite running the A11 bios, it still prompts me to hit F1 on each startup.

Dell assured me the CPU was compatible, but I'm guessing not? heh

Any advice is appreciated


All Replies
  • You can try resetting BIOS.  Power off, unplug, and press/hold power button on tower for ~15 sec. Open the case and remove the motherboard battery. Press/hold power button again for ~30 sec. Reinstall the battery (right-side-up!) and see what happens now.

    If that doesn't help, the new processor probably isn't listed in the BIOS table. If A11 is the latest version, you may be stuck with this  problem.


    If this answers your question, please click  Yes


    Forum Member since 2004

    I am NOT a Dell employee

  • I have a similar problem. My motherboard went bad and I replaced it. I installed the original Pentium D processor from the old motherboard and get the "incompatible Processor" error. I also tried a Pentium 4 that I had in stock and still get the error.

    I tried the solution you recommended, but it still ahs the error.

    Does anyone know what processors ARE compatible with this motherboard?

    Part Number PY428


  • The OptiPlex™ GX520 system supports the

    Intel® Pentium® 4 (Prescott) 5xx series

    Intel® Pentium 4 Celeron® 3xx series processors.

    Motherboards made Beginning March 17, 2006,  allow the GX520 to also support the  

    Intel®  Pentium D (Smithfield) 8xx series processors of the NON 130Watt variety.  

    Pentium D also requires the Copper heatpipe  heatsink.

    Pentium 524, 531, 630, 640, 650 and all Celeron D: mainstream heatsink

    Pentium 660, 670 and all Pentium D: performance heatsink (with heatpipes)

    The 520 will error out with Pentium D CPU's faster than 2.8ghz and say Incompatible processor.

    The GX620 does not have this issue with Bios A11.

    Update the Bios BEFORE trying to update the CPU.

    NONE of the EXXXX Series will work.  NONE of the CORE2 DUO Series will work.

    If you want core2 duo Get an Optiplex 745 or better.

    Personal Experience tells me that the 520 is not worth upgrading for 3 reasons.

    1.  The Video Slot is PCI-E X1 with the X16 slot removed.

    2.  CPU support only goes to Pentium D 2.8Ghz,

    3.   2 Ram Slots are removed making 2 Gigs Max Ram.


    The list below is what works.

    Intel® Pentium®  D Processor with
    Dual Core Technology Up to 820 faster CPU's will Halt with Unsupported Processor Message.
    (2.8GHz,2X1M,800MHz FSB)
    Intel® Pentium®  4 Processor with Up to 650  faster CPU's will Halt with Unsupported Processor Message.
    Hyper-Threading Technology
    (3.4GHz,2M,800MHz FSB)
    Intel® Celeron®  D Processor Up to 351 faster CPU's will Halt with Unsupported Processor Message.
    (3.2GHz,256K,533MHz FSB)

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