CMOS Checksum Bad

Discussion in 'Windows 7' started by jrrkid9, Aug 1, 2009.

  1. jrrkid9

    jrrkid9 MDL Novice

    Jul 28, 2009
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    #1 jrrkid9, Aug 1, 2009
    Last edited: Aug 1, 2009
    Hi, everyone

    I just flashed my BIOS with a Dell SLIC 2.1 mod. I am using an Asus P4P800 Deluxe Mobo which had revisioin 1008 Bios as default. I downloaded revision 1019 from the Asus website and applied the SLIC with Andyps AMI Tool. I then used the manufacturers recommeneded way to flash the bios which is using the latest afudos.exe on an Ms-Dos Startup Floppy. I booted to the floppy after setting my bios settings to default, and used the command afudos.exe /ip4p81019.rom to flash the BIOS. Everything completed succesfully and then after I rebooted the machine it showed CMOS Checksum Bad on the test screen. It said press f1 to configure BIOS settings or F2 to load default configuration. I assumed that meant that it would reflash back to original bios so I pressed F2. Now the computer boots up to Windows 7 just fine and I dont get a CMOS Checksum Bad message anymore. Also the BIOS revision is still indeed the new one.

    So basically Im a little confused. What happened when I pressed F2?? Is my mobo/pc safe? What about the CMOS Checksum bad message? What happened to that? Why did I get a CMOS Checksum bad error? Could anybody explain this to me, Id really appreciate it. Thanks everyone.
     
  2. meowie

    meowie MDL Junior Member

    Jul 12, 2009
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    Yeah it's safe , when you flash bios it's good to clear cmos and load defaults first boot .

    So that did one of the things :)

    I usually didn't clear cmos since it was a burden and never had issues but with this board pressing power and reset will do it , so eas job now .
     
  3. jrrkid9

    jrrkid9 MDL Novice

    Jul 28, 2009
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    So loadings default configuration by pressing F2 cleared the CMOS? Why did the error appear in the first place? And how would you clear cmos on some other boards? What if you dont clear cmos?
     
  4. meowie

    meowie MDL Junior Member

    Jul 12, 2009
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    #4 meowie, Aug 1, 2009
    Last edited: Aug 1, 2009
    It did not clear the cmos , it just reset everything to default .

    And that error is normal when you flash a new bios in most cases .

    (At least from personal experience)
     
  5. loopy

    loopy MDL Novice

    Dec 4, 2007
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    CMOS is the collection of settings held in volatile memory with the coin battery. If the new BIOS does not agree with anything in the current CMOS, or CMOS just becomes corrupted, then it needs to be reset to work with the BIOS. [tangent] I remember in the nForce2 days when users freaked at the boards stopping booting and they thought the BIOS was corrupted when it was usually just the CMOS. Cutting power and removing the battery or changing the CMOS jumper for a few seconds would reset it.[/tangent] In fact a couple of modded BIOS I've used over the years have forced a CMOS checksum error purposefully to get you to manually reset in order for the mods to take effect (memory timings etc.). This is why I always use a batch file for flashing with the /cc switch (for Award BIOS) to clear CMOS so I don't have to mess with the jumper. If F2 serves the same function, that makes it all the easier. Nothing to worry about really.