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How can I use 2 power supplies at once

Discussion in 'Overclocking' started by Dirty Harry, Jul 31, 2007.

  1. Dirty Harry

    Dirty Harry Guest

    I don't have money of a new PS but I have plenty of old ones lying around.
    I'd like to use the 350 for the computer and a 250 for the hard drives
    (5)...I know the green wire has something to do with starting up the
    ps...help me out guys :).
    Dirty Harry, Jul 31, 2007
    #1
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  2. Dirty Harry

    Eric Parker Guest

    "Dirty Harry" <> wrote in message
    news:_PAri.19239$fJ5.9990@pd7urf1no...
    >I don't have money of a new PS but I have plenty of old ones lying
    >around. I'd like to use the 350 for the computer and a 250 for the hard
    >drives (5)...I know the green wire has something to do with starting up
    >the ps...help me out guys :).
    >
    >


    Take this with all the usual health warnings, at your own risk etc.

    My approach would be to connect the 2 greens together and one plugs into
    the M/B.
    I'm sure somebody else may have more to say on this.

    Personally I'd get a cheap large PSU and save the grief.

    Eric

    --
    Remove the dross to contact me directly
    Eric Parker, Jul 31, 2007
    #2
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  3. Dirty Harry

    Phil Weldon Guest

    'Dirty Harry' wrote:
    | I don't have money of a new PS but I have plenty of old ones lying around.
    | I'd like to use the 350 for the computer and a 250 for the hard drives
    | (5)...I know the green wire has something to do with starting up the
    | ps...help me out guys :).
    _____

    If you use one power supply for the motherboard and slots, another for the
    drives, you should be ok. It is a bad idea to connect two power supplies in
    parallel to the motherboard.

    #1. You might have a alternative for the drives. Drives don't use much
    power except when spinning up. Some BIOS have a setting to delay hard drive
    spin-up (spin-up is staggered over a short period of time.

    #2. Check at the manufacturer web site for each of your hard drives and add
    up the power consumption. You will find that most drives use less power
    than you think.

    #3. Keep in mind that at the time your graphics card might be demanding the
    most power that it is unlikely that you will have many of the drives using
    more than average power.

    #4. An ATX12V power supply has 'load sharing'. That means power is shifted
    to what ever voltage rails require it. The TOTAL power output is limited to
    the over all supply rating, but individual voltages can use up to perhaps
    80% of the total supply rating.


    I recommend you check the amount of power your really need before
    jury-rigging two power supplies. And check to see if the larger single
    power supply alone causes any problems.

    See
    http://www.formfactors.org/developer/specs/ATX12V PSDG2.01.pdf
    for ATX12V specifications and information on
    load sharing
    connector pin-out
    Power ON#
    Power Good.

    Phil Weldon



    "Dirty Harry" <> wrote in message
    news:_PAri.19239$fJ5.9990@pd7urf1no...
    |I don't have money of a new PS but I have plenty of old ones lying around.
    | I'd like to use the 350 for the computer and a 250 for the hard drives
    | (5)...I know the green wire has something to do with starting up the
    | ps...help me out guys :).
    |
    |
    Phil Weldon, Jul 31, 2007
    #3
  4. Dirty Harry

    Dirty Harry Guest

    "Phil Weldon" <> wrote in message
    news:15Lri.12778$...
    > 'Dirty Harry' wrote:
    > | I don't have money of a new PS but I have plenty of old ones lying
    > around.
    > | I'd like to use the 350 for the computer and a 250 for the hard drives
    > | (5)...I know the green wire has something to do with starting up the
    > | ps...help me out guys :).
    > _____
    >
    > If you use one power supply for the motherboard and slots, another for the
    > drives, you should be ok. It is a bad idea to connect two power supplies
    > in
    > parallel to the motherboard.
    >
    > #1. You might have a alternative for the drives. Drives don't use much
    > power except when spinning up. Some BIOS have a setting to delay hard
    > drive
    > spin-up (spin-up is staggered over a short period of time.
    >
    > #2. Check at the manufacturer web site for each of your hard drives and
    > add
    > up the power consumption. You will find that most drives use less power
    > than you think.
    >
    > #3. Keep in mind that at the time your graphics card might be demanding
    > the
    > most power that it is unlikely that you will have many of the drives using
    > more than average power.
    >
    > #4. An ATX12V power supply has 'load sharing'. That means power is
    > shifted
    > to what ever voltage rails require it. The TOTAL power output is limited
    > to
    > the over all supply rating, but individual voltages can use up to perhaps
    > 80% of the total supply rating.
    >
    >
    > I recommend you check the amount of power your really need before
    > jury-rigging two power supplies. And check to see if the larger single
    > power supply alone causes any problems.
    >
    > See
    > http://www.formfactors.org/developer/specs/ATX12V PSDG2.01.pdf
    > for ATX12V specifications and information on
    > load sharing
    > connector pin-out
    > Power ON#
    > Power Good.
    >
    > Phil Weldon



    My problem is that the 12v line is dropping all the way down to 11.5 when
    the system is under load. I have 2 raid arrays and one usb HD so there is a
    total of 5 drives all together. I think i'm going to do this, set a power
    supply for the hard drives on a switch (green connected to a ground) and
    then fire that up first and then turn on the computer power. The system is
    always running 24/7 so it shouldn't be too much of an issue for booting up.
    What do ya think?
    Dirty Harry, Jul 31, 2007
    #4
  5. Dirty Harry

    Phil Weldon Guest

    'DeanB' wrote:
    | My problem is that the 12v line is dropping all the way down to 11.5 when
    | the system is under load. I have 2 raid arrays and one usb HD so there is
    a
    | total of 5 drives all together. I think i'm going to do this, set a power
    | supply for the hard drives on a switch (green connected to a ground) and
    | then fire that up first and then turn on the computer power. The system
    is
    | always running 24/7 so it shouldn't be too much of an issue for booting
    up.
    | What do ya think?
    _____

    The specifications of ATX12V for the 12 volt lines are 12 volts +/- 5%, or
    11.4 to 12.6 volts, so your readings are within specifications ( see
    <http://www.formfactors.org/developer/specs/ATX12V%20PSDG2.01.pdf>
    3.2.1 DC Voltage Regulation
    page 12)

    If you are not actually having problems, I wouldn't change things. (The USB
    hard drive has its own power supply, a wall wart, right?)

    If you do use the second power supply, I think your method is the way to go.

    Phil Weldon

    "Dirty Harry" <> wrote in message
    news:QKLri.18691$_d2.5693@pd7urf3no...
    |
    | "Phil Weldon" <> wrote in message
    | news:15Lri.12778$...
    | > 'Dirty Harry' wrote:
    | > | I don't have money of a new PS but I have plenty of old ones lying
    | > around.
    | > | I'd like to use the 350 for the computer and a 250 for the hard drives
    | > | (5)...I know the green wire has something to do with starting up the
    | > | ps...help me out guys :).
    | > _____
    | >
    | > If you use one power supply for the motherboard and slots, another for
    the
    | > drives, you should be ok. It is a bad idea to connect two power
    supplies
    | > in
    | > parallel to the motherboard.
    | >
    | > #1. You might have a alternative for the drives. Drives don't use much
    | > power except when spinning up. Some BIOS have a setting to delay hard
    | > drive
    | > spin-up (spin-up is staggered over a short period of time.
    | >
    | > #2. Check at the manufacturer web site for each of your hard drives and
    | > add
    | > up the power consumption. You will find that most drives use less power
    | > than you think.
    | >
    | > #3. Keep in mind that at the time your graphics card might be demanding
    | > the
    | > most power that it is unlikely that you will have many of the drives
    using
    | > more than average power.
    | >
    | > #4. An ATX12V power supply has 'load sharing'. That means power is
    | > shifted
    | > to what ever voltage rails require it. The TOTAL power output is
    limited
    | > to
    | > the over all supply rating, but individual voltages can use up to
    perhaps
    | > 80% of the total supply rating.
    | >
    | >
    | > I recommend you check the amount of power your really need before
    | > jury-rigging two power supplies. And check to see if the larger single
    | > power supply alone causes any problems.
    | >
    | > See
    | > http://www.formfactors.org/developer/specs/ATX12V PSDG2.01.pdf
    | > for ATX12V specifications and information on
    | > load sharing
    | > connector pin-out
    | > Power ON#
    | > Power Good.
    | >
    | > Phil Weldon
    |
    |
    | My problem is that the 12v line is dropping all the way down to 11.5 when
    | the system is under load. I have 2 raid arrays and one usb HD so there is
    a
    | total of 5 drives all together. I think i'm going to do this, set a power
    | supply for the hard drives on a switch (green connected to a ground) and
    | then fire that up first and then turn on the computer power. The system
    is
    | always running 24/7 so it shouldn't be too much of an issue for booting
    up.
    | What do ya think?
    |
    |
    Phil Weldon, Jul 31, 2007
    #5
  6. Dirty Harry

    Phil Weldon Guest

    'DeanB' wrote:
    | My problem is that the 12v line is dropping all the way down to 11.5 when
    | the system is under load. I have 2 raid arrays and one usb HD so there
    | is a total of 5 drives all together. I think i'm going to do this, set a
    power
    | supply for the hard drives on a switch (green connected to a ground) and
    | then fire that up first and then turn on the computer power. The system
    | is always running 24/7 so it shouldn't be too much of an issue for booting
    | up. What do ya think?
    _____

    The specifications of ATX12V for the 12 volt lines are 12 volts +/- 5%, or
    11.4 to 12.6 volts, so your readings are within specifications ( see
    <http://www.formfactors.org/developer/specs/ATX12V%20PSDG2.01.pdf>
    3.2.1 DC Voltage Regulation
    page 12)

    If you are not actually having problems, I wouldn't change things. (The USB
    hard drive has its own power supply, a wall wart, right?)

    If you do use the second power supply, I think your method is the way to go.

    Phil Weldon

    "Dirty Harry" <> wrote in message
    news:QKLri.18691$_d2.5693@pd7urf3no...
    |
    | "Phil Weldon" <> wrote in message
    | news:15Lri.12778$...
    | > 'Dirty Harry' wrote:
    | > | I don't have money of a new PS but I have plenty of old ones lying
    | > around.
    | > | I'd like to use the 350 for the computer and a 250 for the hard drives
    | > | (5)...I know the green wire has something to do with starting up the
    | > | ps...help me out guys :).
    | > _____
    | >
    | > If you use one power supply for the motherboard and slots, another for
    the
    | > drives, you should be ok. It is a bad idea to connect two power
    supplies
    | > in
    | > parallel to the motherboard.
    | >
    | > #1. You might have a alternative for the drives. Drives don't use much
    | > power except when spinning up. Some BIOS have a setting to delay hard
    | > drive
    | > spin-up (spin-up is staggered over a short period of time.
    | >
    | > #2. Check at the manufacturer web site for each of your hard drives and
    | > add
    | > up the power consumption. You will find that most drives use less power
    | > than you think.
    | >
    | > #3. Keep in mind that at the time your graphics card might be demanding
    | > the
    | > most power that it is unlikely that you will have many of the drives
    using
    | > more than average power.
    | >
    | > #4. An ATX12V power supply has 'load sharing'. That means power is
    | > shifted
    | > to what ever voltage rails require it. The TOTAL power output is
    limited
    | > to
    | > the over all supply rating, but individual voltages can use up to
    perhaps
    | > 80% of the total supply rating.
    | >
    | >
    | > I recommend you check the amount of power your really need before
    | > jury-rigging two power supplies. And check to see if the larger single
    | > power supply alone causes any problems.
    | >
    | > See
    | > http://www.formfactors.org/developer/specs/ATX12V PSDG2.01.pdf
    | > for ATX12V specifications and information on
    | > load sharing
    | > connector pin-out
    | > Power ON#
    | > Power Good.
    | >
    | > Phil Weldon
    |
    |
    | My problem is that the 12v line is dropping all the way down to 11.5 when
    | the system is under load. I have 2 raid arrays and one usb HD so there is
    a
    | total of 5 drives all together. I think i'm going to do this, set a power
    | supply for the hard drives on a switch (green connected to a ground) and
    | then fire that up first and then turn on the computer power. The system
    is
    | always running 24/7 so it shouldn't be too much of an issue for booting
    up.
    | What do ya think?
    |
    |
    Phil Weldon, Jul 31, 2007
    #6
  7. Dirty Harry

    Dirty Harry Guest

    "Phil Weldon" <> wrote in message
    news:w3Mri.14336$...
    > 'DeanB' wrote:
    > | My problem is that the 12v line is dropping all the way down to 11.5
    > when
    > | the system is under load. I have 2 raid arrays and one usb HD so there
    > | is a total of 5 drives all together. I think i'm going to do this, set
    > a
    > power
    > | supply for the hard drives on a switch (green connected to a ground) and
    > | then fire that up first and then turn on the computer power. The
    > system
    > | is always running 24/7 so it shouldn't be too much of an issue for
    > booting
    > | up. What do ya think?
    > _____
    >
    > The specifications of ATX12V for the 12 volt lines are 12 volts +/- 5%, or
    > 11.4 to 12.6 volts, so your readings are within specifications ( see
    > <http://www.formfactors.org/developer/specs/ATX12V%20PSDG2.01.pdf>
    > 3.2.1 DC Voltage Regulation
    > page 12)
    >
    > If you are not actually having problems, I wouldn't change things. (The
    > USB
    > hard drive has its own power supply, a wall wart, right?)
    >
    > If you do use the second power supply, I think your method is the way to
    > go.
    >
    > Phil Weldon
    >



    I'm not having any problems at stock speeds, I can't OC this thing at all
    though lol. Just feel like having some fun squeezing some extra speed out
    of it. Its an amd 3800+ 64 bit....My GF's 3700+ can overclock like crazy
    (230+fsb) I turn this one up to 203 fsb and I'm crashing lol. The problem
    is I'm only using a generic 400w ps I think...I just wanna see if that's my
    OC problem or not...I know I know, get a real power supply hehe...I will
    when I have some moola. :)
    Thanks for the advice!
    Cheers
    Dirty Harry, Jul 31, 2007
    #7
  8. Dirty Harry

    Phil Weldon Guest

    'Dirty Harry' wrote:
    | I'm not having any problems at stock speeds, I can't OC this thing at all
    | though lol. Just feel like having some fun squeezing some extra speed out
    | of it. Its an amd 3800+ 64 bit....My GF's 3700+ can overclock like crazy
    | (230+fsb) I turn this one up to 203 fsb and I'm crashing lol. The
    problem
    | is I'm only using a generic 400w ps I think...I just wanna see if that's
    my
    | OC problem or not...I know I know, get a real power supply hehe...I will
    | when I have some moola. :)
    | Thanks for the advice!
    _____

    It's worth trying. I'd suggest that you might putting as many drives as
    possible in standby, and then checking the 12 volts supply reading. And
    then doing the same when trying to overclock. It might turn out to be a
    voltage quality rather than quantity issue, or the phase of the moon B^) I
    will admit that in days gone by I've used some $12 US power supplies to
    overclock Celeron 'Coppermine' and Pentium III CPUs with no issues. These
    days nearly all power drawn from the + 12 volt line is down converted and
    regulated again before use (save for the drive motors, and those are
    inherently regulated by the speed controller) so I never worry too much
    about power supply quality except for the safety aspects (component failure
    in the power supply should not cause sparks and flames.)

    Phil Weldon

    "Dirty Harry" <> wrote in message
    news:XkMri.18755$_d2.14379@pd7urf3no...
    |
    | "Phil Weldon" <> wrote in message
    | news:w3Mri.14336$...
    | > 'DeanB' wrote:
    | > | My problem is that the 12v line is dropping all the way down to 11.5
    | > when
    | > | the system is under load. I have 2 raid arrays and one usb HD so
    there
    | > | is a total of 5 drives all together. I think i'm going to do this,
    set
    | > a
    | > power
    | > | supply for the hard drives on a switch (green connected to a ground)
    and
    | > | then fire that up first and then turn on the computer power. The
    | > system
    | > | is always running 24/7 so it shouldn't be too much of an issue for
    | > booting
    | > | up. What do ya think?
    | > _____
    | >
    | > The specifications of ATX12V for the 12 volt lines are 12 volts +/- 5%,
    or
    | > 11.4 to 12.6 volts, so your readings are within specifications ( see
    | > <http://www.formfactors.org/developer/specs/ATX12V%20PSDG2.01.pdf>
    | > 3.2.1 DC Voltage Regulation
    | > page 12)
    | >
    | > If you are not actually having problems, I wouldn't change things. (The
    | > USB
    | > hard drive has its own power supply, a wall wart, right?)
    | >
    | > If you do use the second power supply, I think your method is the way to
    | > go.
    | >
    | > Phil Weldon
    | >
    |
    |
    | I'm not having any problems at stock speeds, I can't OC this thing at all
    | though lol. Just feel like having some fun squeezing some extra speed out
    | of it. Its an amd 3800+ 64 bit....My GF's 3700+ can overclock like crazy
    | (230+fsb) I turn this one up to 203 fsb and I'm crashing lol. The
    problem
    | is I'm only using a generic 400w ps I think...I just wanna see if that's
    my
    | OC problem or not...I know I know, get a real power supply hehe...I will
    | when I have some moola. :)
    | Thanks for the advice!
    | Cheers
    |
    |
    Phil Weldon, Jul 31, 2007
    #8
  9. Dirty Harry

    Guest

    Hey Guy
    Not too sure if this helps.
    I ran 2 250WATT PSU on my old system if you solder the "startup" and
    ground wires in the 24 pin plugs of the two supplies together when you
    power up the motherboard both supplies will turn on. i ran this system
    for over 2 years but i was running the system off the main supply and
    all the fans, lights, water pump off the second one. what you could
    probably do is run the system off one PSU and your GPU off the other.
    Cheers
    , Aug 1, 2007
    #9
  10. Dirty Harry

    Dirty Harry Guest

    <> wrote in message
    news:...
    > Hey Guy
    > Not too sure if this helps.
    > I ran 2 250WATT PSU on my old system if you solder the "startup" and
    > ground wires in the 24 pin plugs of the two supplies together when you
    > power up the motherboard both supplies will turn on. i ran this system
    > for over 2 years but i was running the system off the main supply and
    > all the fans, lights, water pump off the second one. what you could
    > probably do is run the system off one PSU and your GPU off the other.
    > Cheers



    Hey thats not a bad idea either, the video card is the next biggest power
    sucker next to the cpu I'm guessin. Hopefully there wouldn't be any ground
    issues with the card getting power from both supplies...guess I could try
    and find out, its only a 7600 vid card.
    Dirty Harry, Aug 1, 2007
    #10
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