Checksum error after battery replacement

Archived from groups: alt.comp.periphs.mainboard,alt.comp.periphs.mainboard.asus (More info?)

After replacing the battery of the ASUS SP97-V mainboard with a newly
purchased battery from Wal-Mart, I continue to get a checksum error during
POST. The error seems to occur after the power has been shutdown completely.
However, if the PC is restarted immediately, then it will usually not
exhibit the problem.

Is the power supply supposed to provide a recharging function?
Should I install another new battery?
Is there something wrong with the mainboard's CMOS?
5 answers Last reply
More about checksum error battery replacement
  1. Archived from groups: alt.comp.periphs.mainboard,alt.comp.periphs.mainboard.asus (More info?)

    In article <58h7d.211$UP1.165@newsread1.news.pas.earthlink.net>, "knack"
    <zok9NOSPAM@hotmail.com> wrote:

    > After replacing the battery of the ASUS SP97-V mainboard with a newly
    > purchased battery from Wal-Mart, I continue to get a checksum error during
    > POST. The error seems to occur after the power has been shutdown completely.
    > However, if the PC is restarted immediately, then it will usually not
    > exhibit the problem.
    >
    > Is the power supply supposed to provide a recharging function?
    > Should I install another new battery?
    > Is there something wrong with the mainboard's CMOS?

    The power supply should never charge the CMOS coin cell, because
    it could explode. There is a dual diode, a device with three legs,
    usually near the CMOS coin cell, and it prevents the back flow
    of current into the battery. Either +5VSB or the coin cell, power
    the CMOS well on the Southbridge. The "well" is a section of silicon
    which is separately powered from the rest of the chip, and special
    design techniques have to be used for the logic signals inside
    the "well", to be accessable to the rest of the chip. For example,
    when the computer reads out the battery backed real time clock, that
    data crosses the boundary inside the Southbridge.

    The spec on a typical Southbridge is the "well" runs on from
    about 3V down to 2V. Allowing for some voltage drop across the
    diode, that means the battery should have about 2.4V minimum,
    to keep the clock running and the CMOS valid. (I'm assuming
    a 0.4V drop across the dual diode, at low current.)

    Have you tried refreshing the settings ? Write down all your
    custom settings in the BIOS, and then do a "Load Setup Defaults"
    from the Exit menu. See if that makes the CMOS happy. Clearing
    the CMOS is effectively what you did when you changed the battery,
    so I cannot see repeating that doing anything positive.

    About the only other thing that comes to mind, is maybe the dual
    diode is damaged. Asus leaves a ticking time bomb in many motherboards,
    in the form of the dual diode. If you do a "clear CMOS" operation,
    without unplugging the computer, or at least turning off the supply
    so the green LED stops glowing, the computer can be damaged when
    you use the CLRTC jumper. If the green LED is glowing, then the
    CLRTC jumper shorts +5VSB to ground, through the dual diode. The
    dual diode can actually get burnt to the point that the tiny lettering
    on it can no longer be read. Once the dual diode is damaged, then
    the CMOS well generally no longer get the power it needs. In that
    case, you would probably no longer have a working clock between
    power off events.

    HTH,
    Paul
  2. Archived from groups: alt.comp.periphs.mainboard,alt.comp.periphs.mainboard.asus (More info?)

    "Paul" <nospam@needed.com> wrote in message
    news:nospam-0110041516510001@192.168.1.177...
    > In article <58h7d.211$UP1.165@newsread1.news.pas.earthlink.net>, "knack"
    > <zok9NOSPAM@hotmail.com> wrote:
    >
    > > After replacing the battery of the ASUS SP97-V mainboard with a newly
    > > purchased battery from Wal-Mart, I continue to get a checksum error
    during
    > > POST. The error seems to occur after the power has been shutdown
    completely.
    > > However, if the PC is restarted immediately, then it will usually not
    > > exhibit the problem.
    > >
    > > Is the power supply supposed to provide a recharging function?
    > > Should I install another new battery?
    > > Is there something wrong with the mainboard's CMOS?
    >
    > The power supply should never charge the CMOS coin cell, because
    > it could explode. There is a dual diode, a device with three legs,
    > usually near the CMOS coin cell, and it prevents the back flow
    > of current into the battery. Either +5VSB or the coin cell, power
    > the CMOS well on the Southbridge. The "well" is a section of silicon
    > which is separately powered from the rest of the chip, and special
    > design techniques have to be used for the logic signals inside
    > the "well", to be accessable to the rest of the chip. For example,
    > when the computer reads out the battery backed real time clock, that
    > data crosses the boundary inside the Southbridge.
    >
    > The spec on a typical Southbridge is the "well" runs on from
    > about 3V down to 2V. Allowing for some voltage drop across the
    > diode, that means the battery should have about 2.4V minimum,
    > to keep the clock running and the CMOS valid. (I'm assuming
    > a 0.4V drop across the dual diode, at low current.)
    >
    > Have you tried refreshing the settings ? Write down all your
    > custom settings in the BIOS, and then do a "Load Setup Defaults"
    > from the Exit menu. See if that makes the CMOS happy. Clearing
    > the CMOS is effectively what you did when you changed the battery,
    > so I cannot see repeating that doing anything positive.
    >
    > About the only other thing that comes to mind, is maybe the dual
    > diode is damaged. Asus leaves a ticking time bomb in many motherboards,
    > in the form of the dual diode. If you do a "clear CMOS" operation,
    > without unplugging the computer, or at least turning off the supply
    > so the green LED stops glowing, the computer can be damaged when
    > you use the CLRTC jumper. If the green LED is glowing, then the
    > CLRTC jumper shorts +5VSB to ground, through the dual diode. The
    > dual diode can actually get burnt to the point that the tiny lettering
    > on it can no longer be read. Once the dual diode is damaged, then
    > the CMOS well generally no longer get the power it needs. In that
    > case, you would probably no longer have a working clock between
    > power off events.
    >
    > HTH,
    > Paul

    Thanks, Paul, for all that very unusual knowledge. I saved it to a Notepad
    file.

    Whenever I open the cabinet I unplug the power cord. So, yes, the power
    supply was deenergized when I changed the battery.

    I've had my custom BIOS settings penciled into the mainboard's manual for
    several years. I haven't made any changes there since 2000.

    I forgot to mention that whenever the checksum error appears, my custom BIOS
    settings become lost, so then I must spend 10 minutes reentering the BIOS
    settings in order to boot the computer. It never occurred to me to load the
    BIOS default settings as you suggested, because if I did my IRQ-jumpered ISA
    slot modem will not work. WinNT4 is not plug and play, so I must configure
    the modem and set the BIOS to dedicate IRQ-11 to ISA.

    This morning the PC started up normally, but if I get the checksum error
    again tomorrow, I'll load the BIOS defaults as an experiment.
  3. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    "knack" <zok9NOSPAM@hotmail.com> wrote:
    > After replacing the battery of the ASUS SP97-V mainboard with a newly
    > purchased battery from Wal-Mart, I continue to get a checksum error

    Did you measure the voltage of the new battery?
    Perhaps the battery is too old, or of the wrong type (Ag or Mn instead
    of Li).

    Tom
  4. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    On Sat, 09 Oct 2004 23:00:28 +0200, Tom <Tom_Richter@gmx.de> wrote:

    >"knack" <zok9NOSPAM@hotmail.com> wrote:
    >> After replacing the battery of the ASUS SP97-V mainboard with a newly
    >> purchased battery from Wal-Mart, I continue to get a checksum error
    >
    >Did you measure the voltage of the new battery?
    >Perhaps the battery is too old, or of the wrong type (Ag or Mn instead
    >of Li).

    To the OP: are you getting a CMOS Checksum Error - or a BIOS Checksum Error?
    If the former, verify the battery is putting out roughly 3V. Then, if you can
    get into the CMOS Setup Utility, try the "set defaults" operation. If that
    doesn't help, try manually clearing the CMOS (read the user's manual for the
    procedure).

    If the latter, the battery has no bearing on the flash rom contents...
  5. Archived from groups: alt.comp.periphs.mainboard,alt.comp.periphs.mainboard.asus (More info?)

    "Paul" <nospam@needed.com> wrote in message
    news:nospam-0110041516510001@192.168.1.177...
    > In article <58h7d.211$UP1.165@newsread1.news.pas.earthlink.net>, "knack"
    > <zok9NOSPAM@hotmail.com> wrote:
    >
    > > After replacing the battery of the ASUS SP97-V mainboard with a newly
    > > purchased battery from Wal-Mart, I continue to get a checksum error
    during
    > > POST. The error seems to occur after the power has been shutdown
    completely.
    > > However, if the PC is restarted immediately, then it will usually not
    > > exhibit the problem.
    > >
    > > Is the power supply supposed to provide a recharging function?
    > > Should I install another new battery?
    > > Is there something wrong with the mainboard's CMOS?
    >
    > The power supply should never charge the CMOS coin cell, because
    > it could explode. There is a dual diode, a device with three legs,
    > usually near the CMOS coin cell, and it prevents the back flow
    > of current into the battery. Either +5VSB or the coin cell, power
    > the CMOS well on the Southbridge. The "well" is a section of silicon
    > which is separately powered from the rest of the chip, and special
    > design techniques have to be used for the logic signals inside
    > the "well", to be accessable to the rest of the chip. For example,
    > when the computer reads out the battery backed real time clock, that
    > data crosses the boundary inside the Southbridge.
    >
    > The spec on a typical Southbridge is the "well" runs on from
    > about 3V down to 2V. Allowing for some voltage drop across the
    > diode, that means the battery should have about 2.4V minimum,
    > to keep the clock running and the CMOS valid. (I'm assuming
    > a 0.4V drop across the dual diode, at low current.)
    >
    > Have you tried refreshing the settings ? Write down all your
    > custom settings in the BIOS, and then do a "Load Setup Defaults"
    > from the Exit menu. See if that makes the CMOS happy. Clearing
    > the CMOS is effectively what you did when you changed the battery,
    > so I cannot see repeating that doing anything positive.
    >
    > About the only other thing that comes to mind, is maybe the dual
    > diode is damaged. Asus leaves a ticking time bomb in many motherboards,
    > in the form of the dual diode. If you do a "clear CMOS" operation,
    > without unplugging the computer, or at least turning off the supply
    > so the green LED stops glowing, the computer can be damaged when
    > you use the CLRTC jumper. If the green LED is glowing, then the
    > CLRTC jumper shorts +5VSB to ground, through the dual diode. The
    > dual diode can actually get burnt to the point that the tiny lettering
    > on it can no longer be read. Once the dual diode is damaged, then
    > the CMOS well generally no longer get the power it needs. In that
    > case, you would probably no longer have a working clock between
    > power off events.
    >
    > HTH,
    > Paul

    The new replacement battery (Energizer CR2032, from Wal-Mart) turned out to
    be defective (poorly charged). So I got another new battery (Energizer 2032,
    from K-Mart) and replaced the one that continued to result in the error...
    no more problem!
Ask a new question

Read More

Asus Battery Checksum Motherboards