• Clear BIOS on Asus &Z170K

    From Jeff Gaines@21:1/5 to All on Tue Jan 7 14:00:37 2025
    XPost: uk.d-i-y

    I seem to have completely screwed the BIOS on my Z170k by fitting the LSI
    SAS 9207-8i RAID card from my Dell to it.

    I have taken everything out except the boot NVMe but it just sits there
    saying press Delete or F2 for BIOS (it doesn't recognise either). Once it
    came up with a message about re-building an array, press F1 but that did nothing either.

    I removed the CMOS battery, there is no clear CMOS button, will have to
    try and see if there's a clear CMOS jumper.

    Any suggestions appreciated, I am transferring all my kit to my Z170P
    which will be better as a server since it doesn't over-clock so has a
    simpler BIOS!

    --
    Jeff Gaines Dorset UK
    Most people have heard of Karl Marx the philosopher but few know of his
    sister Onya the Olympic runner.
    Her name is still mentioned at the start of every race.

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  • From Andy Burns@21:1/5 to Jeff Gaines on Tue Jan 7 14:20:02 2025
    XPost: uk.d-i-y

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will have to
    try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.

    Any suggestions appreciated

    does capslock LED respond to capslock key?

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  • From Jeff Gaines@21:1/5 to Andy Burns on Tue Jan 7 15:43:01 2025
    XPost: uk.d-i-y

    On 07/01/2025 in message <lu4rgmFb19U1@mid.individual.net> Andy Burns wrote:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will have to
    try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.

    Any suggestions appreciated

    does capslock LED respond to capslock key?

    Thanks Andy :-)

    Found the clear RTC RAM pins, so took battery out, put a drive jumper
    across the pins (good job I kept them, I knew they'd come in useful one
    day!), took jumper off, put battery back, and it booted first time.

    By then I'd moved everything to the Z170P and got that working so I'll
    leave it for now. I need spare machines, if I treat them like the Meccano
    set I never had I'm bound to break things now and then!

    --
    Jeff Gaines Dorset UK
    Captcha is thinking of stopping the use of pictures with traffic lights as cyclists don't know what they are.

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  • From fred@21:1/5 to Andy Burns on Wed Jan 8 10:53:13 2025
    XPost: uk.d-i-y

    Andy Burns <usenet@andyburns.uk> wrote in news:lu4rgmFb19U1 @mid.individual.net:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will have to
    try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.


    I'd be surprised if that worked as there's usually a series diode to
    prevent reverse charging of the battery under fault conditions (or that's
    the way it certainly used to be done).

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  • From Paul@21:1/5 to fred on Fri Jan 10 01:18:27 2025
    XPost: uk.d-i-y

    On Wed, 1/8/2025 5:53 AM, fred wrote:
    Andy Burns <usenet@andyburns.uk> wrote in news:lu4rgmFb19U1 @mid.individual.net:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will have to
    try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.


    I'd be surprised if that worked as there's usually a series diode to
    prevent reverse charging of the battery under fault conditions (or that's
    the way it certainly used to be done).


    Note that Intel reference schematics are not known for their "realism"
    and real circuits have slightly different details. For example, the
    Port Angeles on this particular schematic is pure imagination and
    not real (not a proper SuperIO). Still, you can use this little
    circuit, to have a discussion about the Clear CMOS jumper and
    what good (if any), shorting the battery terminal would have.

    [Picture]

    https://i.postimg.cc/P5kX0J3s/clear-CMOS-schematic.gif

    When running on battery, the switching transients from the ripple
    counter in the Motorola RTC as small. The 1.0uF capacitor is
    there for this purpose. The 1K ohm resistor at the battery, is
    there to limit the discharge rate from the battery, to at most
    3mA. But it also ruins the output impedance of the battery in
    a sense, and the 1uF capacitor restores the electrical performance.
    When the RTC is receiving write operations, the circuit is powered
    at that point, from something "derived" from +5VSB and the impedance
    of that source is a lot lower than this 1K resistor thing. When the
    circuit is quiet and not much current is drawn, the source impedance
    does not need to be all that low.

    If you short the CMOS jumper while the system is running, the Intel
    schematic has us believe there is a 4.7K resistor to avoid a
    disastrous short. Real schematics don't have the 4.7K resistor.
    The jumper instead is right to ground. A large current flows through
    the top half of the BAT54 dual diode, burning it so you can't
    read the legend on top. The BAT54 is a Schottky with low forward
    voltage drop. The path between "2" and "3" burns if you left
    the power on while doing this.

    I recommend pulling out the PC plug while clearing CMOS, just to
    ensure your BAT54 is not cooked.

    There is an alternate way to clear CMOS, on the more modern chipsets.
    Intel put an actual RESET signal on the PCH for this. It's probably
    on the 3.0V powered "pure CMOS" logic section with no ESD protection
    diodes. This could have relatively low drain characteristics for a
    logic input. Yet, real circuit board designers *still* don't use this.
    They've looked at the characteristics and decided the "old way is best",
    even if one of the fault modes is a burned BAT54.

    Anyway, the audience here is good at circuit analysis, and
    don't need my help to figure out the pathology. a lot of boards
    use that circuit, but not all of them.

    Another nice aspect of this circuit, is on a number of occasions
    (maybe a half dozen times), the instructions in the manual were
    WRONG for this thing :-) You would open the box, and a sheet of
    paper would float out. This is the Addendum to replace the page
    with the Clear CMOS instructions. Don't lose that sheet :-)
    The instructions help you avoid the pathology.

    A digital watch, draws 2uA of current while running. The
    RTC on the motherboard, draws 10uA. Both circuits use a 32768 Hz
    quartz crystal. The 10uA load, means the CMOS CR2032 last for
    a bit less than three years, if you store a PC in the junk room
    with no AC power. The fresh battery voltage is a bit higher than
    3.0V. The battery is good down to 2.3V and continues to run the
    RTC at 2.3V. The BAT54 has 0.3V of drop at low current. The
    PCH stops working for the RTC function, at 2.0V. But the
    battery stops working at 2.3V. Some motherboards refuse to start
    when the battery hits 0V, and this is possibly because VBAT is
    tied to some pin on the SuperIO. And if that pin is logic 0,
    that has something to do with stopping the board. Not every
    board stops at 0V on CR2032, but a few do this. A lot of boards
    will run, and they set the BIOS controls to "default" values.

    Paul

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  • From The Natural Philosopher@21:1/5 to fred on Fri Jan 10 09:56:50 2025
    XPost: uk.d-i-y

    On 10/01/2025 09:26, fred wrote:
    Paul <nospam@needed.invalid> wrote in news:vlqe3k$3sb0a$1@dont-email.me:

    On Wed, 1/8/2025 5:53 AM, fred wrote:
    Andy Burns <usenet@andyburns.uk> wrote in news:lu4rgmFb19U1
    @mid.individual.net:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will
    have to try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.


    I'd be surprised if that worked as there's usually a series diode to
    prevent reverse charging of the battery under fault conditions (or
    that's the way it certainly used to be done).


    Note that Intel reference schematics are not known for their "realism"
    and real circuits have slightly different details. For example, the
    Port Angeles on this particular schematic is pure imagination and
    not real (not a proper SuperIO). Still, you can use this little
    circuit, to have a discussion about the Clear CMOS jumper and
    what good (if any), shorting the battery terminal would have.


    TLDR

    Can you please state succinctly the point you are trying to make.


    I think he its trying to say 'taking the battery out and shorting its
    terminals may not work (because there is a diode in there) and may cause
    damage (because there might not be a resistor or diode in there)'.

    There are usually some shortable header pins or in extremis, simply
    removing the battery and letting the data decay from the CMOS should
    sort it all out.

    Of course these days the data is in flash, and wont decay ever. Only the
    RTC will stop without a battery


    https://dictionary.cambridge.org/dictionary/english/succinct


    --
    Religion is regarded by the common people as true, by the wise as
    foolish, and by the rulers as useful.

    (Seneca the Younger, 65 AD)

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  • From fred@21:1/5 to Paul on Fri Jan 10 09:26:28 2025
    XPost: uk.d-i-y

    Paul <nospam@needed.invalid> wrote in news:vlqe3k$3sb0a$1@dont-email.me:

    On Wed, 1/8/2025 5:53 AM, fred wrote:
    Andy Burns <usenet@andyburns.uk> wrote in news:lu4rgmFb19U1
    @mid.individual.net:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will
    have to try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.


    I'd be surprised if that worked as there's usually a series diode to
    prevent reverse charging of the battery under fault conditions (or
    that's the way it certainly used to be done).


    Note that Intel reference schematics are not known for their "realism"
    and real circuits have slightly different details. For example, the
    Port Angeles on this particular schematic is pure imagination and
    not real (not a proper SuperIO). Still, you can use this little
    circuit, to have a discussion about the Clear CMOS jumper and
    what good (if any), shorting the battery terminal would have.


    TLDR

    Can you please state succinctly the point you are trying to make.

    https://dictionary.cambridge.org/dictionary/english/succinct

    --- SoupGate-Win32 v1.05
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  • From Paul@21:1/5 to The Natural Philosopher on Fri Jan 10 12:42:24 2025
    XPost: uk.d-i-y

    On Fri, 1/10/2025 4:56 AM, The Natural Philosopher wrote:
    On 10/01/2025 09:26, fred wrote:
    Paul <nospam@needed.invalid> wrote in news:vlqe3k$3sb0a$1@dont-email.me:

    On Wed, 1/8/2025 5:53 AM, fred wrote:
    Andy Burns <usenet@andyburns.uk> wrote in news:lu4rgmFb19U1
    @mid.individual.net:

    Jeff Gaines wrote:

    I removed the CMOS battery, there is no clear CMOS button, will
    have to try and see if there's a clear CMOS jumper.

    short the battery terminals while it is removed.


    I'd be surprised if that worked as there's usually a series diode to
    prevent reverse charging of the battery under fault conditions (or
    that's the way it certainly used to be done).


    Note that Intel reference schematics are not known for their "realism"
    and real circuits have slightly different details. For example, the
    Port Angeles on this particular schematic is pure imagination and
    not real (not a proper SuperIO). Still, you can use this little
    circuit, to have a discussion about the Clear CMOS jumper and
    what good (if any), shorting the battery terminal would have.


    TLDR

    Can you please state succinctly the point you are trying to make.


    I think he its trying to say 'taking the battery out and shorting its terminals may not work (because there is a diode in there) and may cause damage (because there might not be a resistor or diode in there)'.

    There are usually some shortable header pins or in extremis, simply removing the battery and letting the data decay from the CMOS should sort it all out.

    Of course these days the data is in flash, and wont decay ever. Only the RTC will stop without a battery


    https://dictionary.cambridge.org/dictionary/english/succinct



    Yes, there is, at minimum, a two pin header. A three pin header
    is used when the company desires a parking location for the provided
    jumper plug.

    There is also a version with a switch on the back of the PC,
    but the circuit behind that one is different.

    Shorting the two pin header, is for clearing the CMOS. On "real" designs,
    the 4.7K resistor shown in the Intel demo schematic is not there,
    and you are shorting the 1uF cap directly to ground. The CR2032 is
    not damaged, as there is the 1K ohm limiting resistor.

    However, if you short the header while the +5VSB is available (and
    it is available even when fans are not spinning!), you can draw an excess
    of current through the top diode in the dual diode package. (Not seen on that schematic sheet, there is some mechanism for regulating +5VSB down to
    a voltage for usage on the top leg of the ORing diode.) This burns
    the diode to the point, you cannot even read the part number off the
    SOT23 package.

    I helped someone with this once. Their dual diode burned. I mentioned
    a part number they could use. They used a couple 1N914 discrete diodes
    and soldered that on as a replacement instead. Those have a higher forward Vdrop,
    shortening the battery replacement interval, but the solution worked for
    the guy and he was happy to be operational again.

    The proper instructions in the manual, say to remove all power, to avoid
    an "incident". If the power plug is pulled, and you short the two pin
    CLR_CMOS header or use a screwdriver tip to short the two pads labeled CLR_CMOS, then that discharges the node on the PCH side and drops the
    voltage on the CMOS well, erasing RTC register contents and CMOS
    RAM contents (256 locations in PCH).

    Most of the time, we expect this "legacy circuit" implementation to be
    used, with its chance of damage. The Intel logic signal added,
    the motherboard designers shy away from that. It's possible the
    machines with the CMOS button on the back, those use the logic signal.
    Intel no longer makes those demo schematics available without an NDA,
    so it is not possible to comment on the latest recommended circuit.

    The provision of the 4.7K resistor, would not pull the node down enough
    to guarantee a reset. It would pull down to 80% of 3V, which is 2.4V
    and still high enough for the CMOS contents to be perfectly happy.
    (Guaranteed retention at 2.0V and over the temperature range.) Real
    circuits use zero ohms and pull the node down hard to ensure it is
    reset. Which is basically what users are attempting to do via poking
    at battery contacts and so on (which is not on the "correct side" of
    the problem). But by using zero ohms, there is a burning risk,
    which is why careful users unplug the power cord first.

    Paul

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  • From fred@21:1/5 to The Natural Philosopher on Sat Jan 11 14:56:45 2025
    XPost: uk.d-i-y

    The Natural Philosopher <tnp@invalid.invalid> wrote in news:vlqqt2$3tscn$6 @dont-email.me:

    On 10/01/2025 09:26, fred wrote:
    Paul <nospam@needed.invalid> wrote in news:vlqe3k$3sb0a$1@dont-email.me:

    On Wed, 1/8/2025 5:53 AM, fred wrote:

    TLDR

    Can you please state succinctly the point you are trying to make.


    I think he its trying to say 'taking the battery out and shorting its terminals may not work (because there is a diode in there) and may cause damage (because there might not be a resistor or diode in there)'.


    So pretty much repeating the content of my own contribution but with the
    /uv (unnecessarily verbose) switch set.

    . . . and oh look another ramble has appeared <plonk>

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  • From The Natural Philosopher@21:1/5 to fred on Sat Jan 11 15:14:59 2025
    XPost: uk.d-i-y

    On 11/01/2025 14:56, fred wrote:

    . . . and oh look another ramble has appeared <plonk>

    good riddance

    --
    Of what good are dead warriors? … Warriors are those who desire battle
    more than peace. Those who seek battle despite peace. Those who thump
    their spears on the ground and talk of honor. Those who leap high the
    battle dance and dream of glory … The good of dead warriors, Mother, is
    that they are dead.
    Sheri S Tepper: The Awakeners.

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