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Overclocking: Leave voltage as is?

Discussion in 'Hardware' started by aether, Mar 27, 2005.

  1. aether

    aether Guest

    I'm running a 3500+ (90nm) processor on an AN8 ('Fatal1ty')
    motherboard, and I've overclocked it from 2.2 to 2.5 GHz. However, the
    voltage remains at 1.4 despite having multiple options in BIOS. Should
    I up the voltage? If so, how much? Could I be damaging the processor by
    leaving the voltage as is? I've not encountered any problems, but it
    does seem as though it would require more juice.
    aether, Mar 27, 2005
    #1
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  2. aether

    Conor Guest

    In article <>,
    aether says...
    > I'm running a 3500+ (90nm) processor on an AN8 ('Fatal1ty')
    > motherboard, and I've overclocked it from 2.2 to 2.5 GHz. However, the
    > voltage remains at 1.4 despite having multiple options in BIOS. Should
    > I up the voltage? If so, how much? Could I be damaging the processor by
    > leaving the voltage as is? I've not encountered any problems, but it
    > does seem as though it would require more juice.
    >

    If it works, leave it alone. Upping the voltage increases heat and
    damages the processor.


    --
    Conor

    Windows & Outlook/OE in particular, shipped with settings making them
    as open to entry as a starlet in a porno. Steve B
    Conor, Mar 27, 2005
    #2
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  3. aether

    Pete D Guest

    Sounds like there is nothing to fix here, move along!!

    "aether" <> wrote in message
    news:...
    > I'm running a 3500+ (90nm) processor on an AN8 ('Fatal1ty')
    > motherboard, and I've overclocked it from 2.2 to 2.5 GHz. However, the
    > voltage remains at 1.4 despite having multiple options in BIOS. Should
    > I up the voltage? If so, how much? Could I be damaging the processor by
    > leaving the voltage as is? I've not encountered any problems, but it
    > does seem as though it would require more juice.
    >
    Pete D, Mar 27, 2005
    #3
  4. aether

    aether Guest

    Will leave as is. At one point, I did increase it to 1.5. Was that
    enough to damage the processor? (the max is 1.8)
    aether, Mar 27, 2005
    #4
  5. aether

    Ben Pope Guest

    aether wrote:
    > Will leave as is. At one point, I did increase it to 1.5. Was that
    > enough to damage the processor? (the max is 1.8)


    Something will shut it down before it is damaged.

    It probably won't be damaged until past 100°C.

    Voltage doesn't damage CPUs, heat does.

    If there is not enough voltage, you will get transient errors (but no
    damage).

    Ben
    --
    A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
    Questions by email will likely be ignored, please use the newsgroups.
    I'm not just a number. To many, I'm known as a String...
    Ben Pope, Mar 27, 2005
    #5
  6. aether

    Paul Guest

    In article <>,
    "aether" <> wrote:

    > Will leave as is. At one point, I did increase it to 1.5. Was that
    > enough to damage the processor? (the max is 1.8)


    You can judge that from the processor datasheet, not from what
    the BIOS is saying. For example, there are tech docs here:

    http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_739_7203,00.html

    Absolute max Vcore is listed on PDF page 51. It is 1.65 volts.
    http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31411.pdf

    If it was my processor, I wouldn't use more than 1.65V. In addition,
    due to overvolting by some Vcore circuits, a safer limit would be
    1.6V. The higher voltages are fine for veteran overclockers on
    unlimited budgets :)

    Next, look at the operating data:

    http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/30430.pdf

    On page 13, I see ADA3500DIK4BI. Maybe that is the 90nm processor,
    I'm not really sure. Look at the operating points. An extra 0.050V
    buys 200MHz of extra core. That is AMD's estimate. If you set the
    voltage to 1.5V, instead of 1.4V, that means you should be able to
    go from 2200 to 2600MHz.

    To test stability, use something like Prime95 (mersenne.org). First
    try your overclock at 1.5V . See if the board runs error free for
    at least several hours. Now, drop the voltage 0.050V at a time
    (or whatever the smallest step the BIOS allows for voltage change).
    Take small steps, so you don't corrupt your operating system.
    (I use a Knoppix read-only linux boot disk for this kind of testing.
    There is a linux version of Prime95 available from mersenne.org .)
    At the point that it starts to error in Prime95, you have reached a
    limit. Now, you want to apply a bit more voltage again. Run Prime95
    again. You should be able to come up with a set of conditions which
    is optimal for your particular processor, and stable for hours on
    end.

    Electromigration is one failure mechanism, and it is my belief
    that the cases you read about, where a processor can no longer
    run at its rated speed, is an example of electromigration damage.
    Electromigration is related to the amount of current flowing in
    the wires that route the logic signals on the silicon die. The
    wires are made wide enough, that the chip can operate at frequencies
    higher than the nominal operating frequency. You should be able
    to operate your processor, at least as fast as the faster speed
    bin version of your processor die. There is no way to estimate
    how much further you can safely go, as each transition (from 130nm
    to 90nm to 65nm and so on) will bring with it, different
    electromigration rules. It doesn't sound like your current overclock
    is too extreme.

    HTH,
    Paul
    Paul, Mar 28, 2005
    #6
  7. "aether" <> wrote in message
    news:...

    > Will leave as is. At one point, I did increase it to 1.5. Was that
    > enough to damage the processor? (the max is 1.8)


    So long as you didn't overheat it, the higher voltage won't damage it
    (since it's still less than the absolute maximum permitted). You should use
    the lowest voltage at which the processor is reliable. Keep a close eye on
    the CPU temperature, especially as summer rolls around and as the fan ages
    and dust accumulates on the heat sink. If the CPU becomes unreliable or the
    temperature gets too high, re-evaluate everything.

    DS
    David Schwartz, Mar 28, 2005
    #7
  8. aether

    aether Guest

    > David Schwartz wrote:
    > "aether" <> wrote in message
    > news:...
    >
    > > Will leave as is. At one point, I did increase it to 1.5. Was that
    > > enough to damage the processor? (the max is 1.8)

    >
    > So long as you didn't overheat it, the higher voltage won't

    damage it
    > (since it's still less than the absolute maximum permitted). You

    should use
    > the lowest voltage at which the processor is reliable. Keep a close

    eye on
    > the CPU temperature, especially as summer rolls around and as the fan

    ages
    > and dust accumulates on the heat sink. If the CPU becomes unreliable

    or the
    > temperature gets too high, re-evaluate everything.
    >
    > DS


    I'm sure it didn't overheat, as I was monitoring it and the highest I
    saw it reach was 53c. At that point, I lowered the voltage back to 1.4.
    The members of this newsgroup have been a big help to me. I appreciate
    it.
    aether, Mar 28, 2005
    #8
  9. aether

    Trent Guest

    On Sun, 27 Mar 2005 23:55:41 +0100 Ben Pope <benpope81@_REMOVE_gmail.com>
    wrote in Message id:
    <1111964140.3094d6d7de75cfdeab25df9bee798ae0@teranews>:

    >Voltage doesn't damage CPUs, heat does.


    You are an utter fucking imbecile.
    Trent, Mar 28, 2005
    #9
  10. aether

    NuTCrAcKeR Guest

    Please visit alt.comp.hardware.overclocking.amd for better information than
    is being presented here.

    - NuTs

    "aether" <> wrote in message
    news:...
    >> David Schwartz wrote:
    >> "aether" <> wrote in message
    >> news:...
    >>
    >> > Will leave as is. At one point, I did increase it to 1.5. Was that
    >> > enough to damage the processor? (the max is 1.8)

    >>
    >> So long as you didn't overheat it, the higher voltage won't

    > damage it
    >> (since it's still less than the absolute maximum permitted). You

    > should use
    >> the lowest voltage at which the processor is reliable. Keep a close

    > eye on
    >> the CPU temperature, especially as summer rolls around and as the fan

    > ages
    >> and dust accumulates on the heat sink. If the CPU becomes unreliable

    > or the
    >> temperature gets too high, re-evaluate everything.
    >>
    >> DS

    >
    > I'm sure it didn't overheat, as I was monitoring it and the highest I
    > saw it reach was 53c. At that point, I lowered the voltage back to 1.4.
    > The members of this newsgroup have been a big help to me. I appreciate
    > it.
    >
    NuTCrAcKeR, Mar 29, 2005
    #10
  11. aether

    Mercury Guest

    Thank you for the clarity and pointedness of your communications. However,
    although I can guess at the intended purpose of your statement I prefer not
    to. In future, perhaps you may wish to put more effort into not just what
    you are trying to communicate, but also how.


    "Trent" <> wrote in message
    news:...
    > On Sun, 27 Mar 2005 23:55:41 +0100 Ben Pope <benpope81@_REMOVE_gmail.com>
    > wrote in Message id:
    > <1111964140.3094d6d7de75cfdeab25df9bee798ae0@teranews>:
    >
    >>Voltage doesn't damage CPUs, heat does.

    >
    > You are an utter fucking imbecile.
    Mercury, Mar 29, 2005
    #11
  12. aether

    - HAL9000 Guest

    Trent, what do you mean? Ben was correct in a common sense or
    practical way. Were you thinking of super cooling the cpu and then
    applying extreme voltages to break down it's barriers, or ?

    Forrest

    Motherboard Help By HAL web site:
    http://home.comcast.net/~mobo.help/


    On Mon, 28 Mar 2005 12:21:56 -0500, Trent <> wrote:

    >On Sun, 27 Mar 2005 23:55:41 +0100 Ben Pope <benpope81@_REMOVE_gmail.com>
    >wrote in Message id:
    ><1111964140.3094d6d7de75cfdeab25df9bee798ae0@teranews>:
    >
    >>Voltage doesn't damage CPUs, heat does.

    >
    >You are an utter fucking imbecile.
    - HAL9000, Mar 29, 2005
    #12
  13. aether

    Stephen Guest

    On Sun, 27 Mar 2005 23:55:41 +0100, Ben Pope
    <benpope81@_REMOVE_gmail.com> had a flock of green cheek conures
    squawk out:

    >Voltage doesn't damage CPUs, heat does.


    Voltage sure can damage a CPU, just hit it with a nice static
    electrical charge and see if it still works.

    Stephen


    --
    Stephen, Mar 29, 2005
    #13
  14. aether

    Ben Pope Guest

    Stephen wrote:
    > On Sun, 27 Mar 2005 23:55:41 +0100, Ben Pope
    > <benpope81@_REMOVE_gmail.com> had a flock of green cheek conures
    > squawk out:
    >
    >
    >>Voltage doesn't damage CPUs, heat does.

    >
    >
    > Voltage sure can damage a CPU, just hit it with a nice static
    > electrical charge and see if it still works.


    And what exactly do you think a few thousand volts discharge through the
    chip *actually* does?

    The voltage potential causes a current to flow. That current flows
    through "thin wires". The "thin wires" have a high resistance. That
    high resistance causes the "thin wires" to heat. The heat damages the
    "thin wires".

    So my point was that heat damages CPUs, not voltage. The voltage causes
    a current, which causes the heat, but the voltage itself didn't cause
    the damage, the heat did. If the source is current limited, you could
    apply a high voltage and not damage the chip.

    Besides, I was assuming that the CPU was in the motherboard when the
    user was adjusting the voltage from 1.4V to 1.5V, not running aimlessly
    around the coffee as fast as he can in his carpeted lounge wearing
    rubber shoes, holding the CPU in his hands, shouting "DIE, DIE".

    He might have been, but it seems unlikely.

    Ben
    --
    A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
    Questions by email will likely be ignored, please use the newsgroups.
    I'm not just a number. To many, I'm known as a String...
    Ben Pope, Mar 29, 2005
    #14
  15. aether

    Guest

    Ben Pope wrote:
    > Stephen wrote:
    > > On Sun, 27 Mar 2005 23:55:41 +0100, Ben Pope
    > > <benpope81@_REMOVE_gmail.com> had a flock of green cheek conures
    > > squawk out:
    > >
    > >
    > >>Voltage doesn't damage CPUs, heat does.

    > >
    > >
    > > Voltage sure can damage a CPU, just hit it with a nice static
    > > electrical charge and see if it still works.

    >
    > And what exactly do you think a few thousand volts discharge through

    the
    > chip *actually* does?
    >
    > The voltage potential causes a current to flow. That current flows
    > through "thin wires". The "thin wires" have a high resistance. That


    > high resistance causes the "thin wires" to heat. The heat damages

    the
    > "thin wires".
    >
    > So my point was that heat damages CPUs, not voltage. The voltage

    causes
    > a current, which causes the heat, but the voltage itself didn't cause


    > the damage, the heat did. If the source is current limited, you

    could
    > apply a high voltage and not damage the chip.
    >
    > Besides, I was assuming that the CPU was in the motherboard when the
    > user was adjusting the voltage from 1.4V to 1.5V, not running

    aimlessly
    > around the coffee as fast as he can in his carpeted lounge wearing
    > rubber shoes, holding the CPU in his hands, shouting "DIE, DIE".
    >
    > He might have been, but it seems unlikely.
    >
    > Ben
    > --
    > A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
    > Questions by email will likely be ignored, please use the newsgroups.
    > I'm not just a number. To many, I'm known as a String...


    Ben,
    While you've given many people good advice, I have to disagree with
    you on this one. You can certainly damage an integrated circuit through
    overvoltage. I'm not talking about a 2 KV zap from a carpet, I'm
    talking about running a chip over its maximum voltage rating. You are
    correct in saying that additional heat will be generated by upping the
    voltage, but you also risk parts failure through exceeding the maximum
    voltage.

    Arnie Berger
    , Mar 30, 2005
    #15
  16. aether

    Ben Pope Guest

    wrote:
    > Ben,
    > While you've given many people good advice, I have to disagree with
    > you on this one. You can certainly damage an integrated circuit through
    > overvoltage. I'm not talking about a 2 KV zap from a carpet, I'm
    > talking about running a chip over its maximum voltage rating. You are
    > correct in saying that additional heat will be generated by upping the
    > voltage, but you also risk parts failure through exceeding the maximum
    > voltage.


    What is the failure mode in that case?

    Ben
    --
    A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
    Questions by email will likely be ignored, please use the newsgroups.
    I'm not just a number. To many, I'm known as a String...
    Ben Pope, Mar 30, 2005
    #16
  17. "Ben Pope" <benpope81@_REMOVE_gmail.com> wrote in message
    news:1112139049.b38fae749dde126d203cd18dd368c6f7@teranews...
    > wrote:
    >> Ben,
    >> While you've given many people good advice, I have to disagree with
    >> you on this one. You can certainly damage an integrated circuit through
    >> overvoltage. I'm not talking about a 2 KV zap from a carpet, I'm
    >> talking about running a chip over its maximum voltage rating. You are
    >> correct in saying that additional heat will be generated by upping the
    >> voltage, but you also risk parts failure through exceeding the maximum
    >> voltage.

    >
    > What is the failure mode in that case?



    Overvoltages can cause damage by causing excessive temperatures;
    however, excessive voltages can also cause damage directly. See, for
    example:

    http://www.findarticles.com/p/articles/mi_m0HPJ/is_n5_v45/ai_16182389

    "The physical effects of ESD and EOS [electrical overstress] on ICs can be
    categorized as thermally induced or electric field induced failures. Among
    the thermally induced failure mechanisms are drain junction damage with
    melted filaments, polysilicon gate filaments, contact metal burnout, and
    fused metallization. Typical field induced ESD-related failure mechanisms
    are dielectric breakdown (gate oxide rupture) and latent hotcarrier damage."

    Dielectric breakdown is caused by the excessive voltage itself, not any
    heat created by the greater voltage. The electrons almost literally punch
    holes.

    http://www.semiconfareast.com/oxidebreakdown.htm

    DS
    David Schwartz, Mar 30, 2005
    #17
  18. aether

    Guest

    Ben Pope wrote:
    > wrote:
    > > Ben,
    > > While you've given many people good advice, I have to disagree

    with
    > > you on this one. You can certainly damage an integrated circuit

    through
    > > overvoltage. I'm not talking about a 2 KV zap from a carpet, I'm
    > > talking about running a chip over its maximum voltage rating. You

    are
    > > correct in saying that additional heat will be generated by upping

    the
    > > voltage, but you also risk parts failure through exceeding the

    maximum
    > > voltage.

    >
    > What is the failure mode in that case?
    >
    > Ben
    > --
    > A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
    > Questions by email will likely be ignored, please use the newsgroups.
    > I'm not just a number. To many, I'm known as a String...



    Several of the other posts answered it. Usually it is either
    punch-through, breaking down the dielectric, or electromigration. I
    suppose that there can also be some local heating effects (ie, the
    thermal conductivity of the substrate is not sufficient for the amount
    of heat generated, but I wasn't referring to heat.

    I'm not an expert on IC breakdown mechanisms but I know that you can
    get a bipolar part to go into latch-up by exceeding its breakdown
    voltage. In effect, it becomes a zener diode, and without a current
    limiting resisitor, it self-destructs.

    arnie
    , Mar 30, 2005
    #18
  19. "Ben Pope" <benpope81@_REMOVE_gmail.com> wrote in message
    news:1112135816.1468a1a8707a324ec1de245ef24e643b@teranews...
    > Stephen wrote:
    > > On Sun, 27 Mar 2005 23:55:41 +0100, Ben Pope
    > > <benpope81@_REMOVE_gmail.com> had a flock of green cheek conures
    > > squawk out:

    [...]
    > The voltage potential causes a current to flow. That current flows
    > through "thin wires". The "thin wires" have a high resistance. That
    > high resistance causes the "thin wires" to heat. The heat damages the
    > "thin wires".
    >
    > So my point was that heat damages CPUs, not voltage. The voltage causes
    > a current, which causes the heat, but the voltage itself didn't cause
    > the damage, the heat did. If the source is current limited, you could
    > apply a high voltage and not damage the chip.


    Metal melts do happen, but junction breakdown and oxide failure are possibly
    more important with ESD. Might a really high voltage cause migration across
    the n and p layers, making the semiconductor diodes non-functional, without
    melting?

    There may be some difference between the operative mechanism for damage from
    the 1000 to 40,000 volts one may produce walking across the carpet
    (dissipated in a millisecond), and damage from supplying an extra 0.5 volts
    (over months). Long-term damage occurs at well below the melting points of
    many of the metals in semiconductors (though perhaps not below the
    temperatures for fast mixing of oxide-metal "alloys"). Latent and/or
    long-term failures are probably by very different mechanisms than those that
    are caused by ESD.
    H.W. Stockman, Mar 30, 2005
    #19
  20. aether

    Paul Guest

    In article <Dqp2e.544$>, "H.W.
    Stockman" <stockman3@earth-REMOVE_THIS-llink.net> wrote:

    > "Ben Pope" <benpope81@_REMOVE_gmail.com> wrote in message
    > news:1112135816.1468a1a8707a324ec1de245ef24e643b@teranews...
    > > Stephen wrote:
    > > > On Sun, 27 Mar 2005 23:55:41 +0100, Ben Pope
    > > > <benpope81@_REMOVE_gmail.com> had a flock of green cheek conures
    > > > squawk out:

    > [...]
    > > The voltage potential causes a current to flow. That current flows
    > > through "thin wires". The "thin wires" have a high resistance. That
    > > high resistance causes the "thin wires" to heat. The heat damages the
    > > "thin wires".
    > >
    > > So my point was that heat damages CPUs, not voltage. The voltage causes
    > > a current, which causes the heat, but the voltage itself didn't cause
    > > the damage, the heat did. If the source is current limited, you could
    > > apply a high voltage and not damage the chip.

    >
    > Metal melts do happen, but junction breakdown and oxide failure are possibly
    > more important with ESD. Might a really high voltage cause migration across
    > the n and p layers, making the semiconductor diodes non-functional, without
    > melting?
    >
    > There may be some difference between the operative mechanism for damage from
    > the 1000 to 40,000 volts one may produce walking across the carpet
    > (dissipated in a millisecond), and damage from supplying an extra 0.5 volts
    > (over months). Long-term damage occurs at well below the melting points of
    > many of the metals in semiconductors (though perhaps not below the
    > temperatures for fast mixing of oxide-metal "alloys"). Latent and/or
    > long-term failures are probably by very different mechanisms than those that
    > are caused by ESD.


    And the mechanism in electromigration, is spelled out in its name.
    There is actual material transport, so as time passes, the composition
    of the "wires" in the IC changes. If a wire becomes thinner, the
    propagation delay of a signal on the wire becomes longer. That
    represents a timing change, and might be compensated for by turning
    down the clock frequency in the affected part of the circuit.

    In the semiconductor fab, great care is taken in choosing the
    dimensions and composition of the "wires". If the circuit operates
    at 3GHz, someone will try to make sure the wires are good to 3.5 or
    4GHz. Since the wire dimensions affect the outside dimensions of
    the silicon die, and the manufacturing economics, there are
    incentives not to overdo it. From an overclockers perspective,
    it means if you put some effort into your overclock, you could
    enter the realm of accelerated life testing.

    My info is years old, and was from a conversation with someone
    at our fab (the head of the cell library development department).
    Since materials and methods have changed a lot since
    then, the design rules and margins used could be very different.
    My info is only intended to illustrate a failure mechanism
    which is different from the breakdown phenomenon the other
    posters have mentioned.

    There is a fine article here, full of wizzy words:
    http://en.wikipedia.org/wiki/Electromigration

    With regard to breakdown, there was one ISSCC paper presented by
    Motorola, where the breakdown voltage was only listed as 0.2V
    greater than absolute max for Vcore. Again, many overclockers will
    choose to ignore Vcore_max, and it is anyone's guess as to when
    they will be hit. Since there are devices like the OCZ DIMM
    booster, and the DFI board that can run RAM at 4 volts, I guess
    all this knowledge about absolute max is irrelevant :)))

    Presented by someone with only a casual interest in the subject,
    Paul
    Paul, Mar 31, 2005
    #20
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