8 pin ATX 12V plug

Discussion in 'Computer Hardware' started by Keiron, Oct 8, 2010.

  1. Keiron

    Keiron Guest

    Hi all, Just picked up a new motherboard (Gigabyte MA785GM-US2H) for a
    low power system. I'm coupling it up with the Athlon 64 2000+ 8 Watt cpu,
    so obviously only single core. I hadn't intended on upgrading the PSU
    just yet but my current supply only has the 4 pin 12V connector (in
    addition to the 24pin obviously). Now i've read that the 8 pin is
    required for multiple cores so seeing as I'll be using a single core cpu
    is itb fine just to use the 4pins or do I risk damage in some way? Thanks
     
    Keiron, Oct 8, 2010
    #1
    1. Advertisements

  2. Keiron

    Paul Guest

    Keiron wrote:
    > Hi all, Just picked up a new motherboard (Gigabyte MA785GM-US2H) for a
    > low power system. I'm coupling it up with the Athlon 64 2000+ 8 Watt cpu,
    > so obviously only single core. I hadn't intended on upgrading the PSU
    > just yet but my current supply only has the 4 pin 12V connector (in
    > addition to the 24pin obviously). Now i've read that the 8 pin is
    > required for multiple cores so seeing as I'll be using a single core cpu
    > is itb fine just to use the 4pins or do I risk damage in some way? Thanks


    Motherboards with a 2x4 power connector, may come with a 2x2 cap,
    covering four of the holes. That is intended to show you, where to plug
    a 2x2 connector, if that is the kind of supply you've got.

    In terms of ampacity, I recommend to people as a rule, that
    each yellow wire can support 6 amps. 6 amps is the figure for
    a MiniFit Jr. pin and wire, on the main power supply connector.
    When a MiniFit connector has a smaller number of pins, there is a
    bit more cooling available around it, and less heat buildup. The
    pins in that case, can be rated for slightly more current. If
    a heavier wire gauge is used, that bumps up the current one
    level as well.

    Rather than waste a lot of time, dwelling on details, it's simpler
    to just tell you to stick with a 6 amp limit. That is a conservative
    figure.

    OK, so now we can do power analysis for the 2x2 connector.

    The 2x2 connector has two yellow wires. It can carry at most, 2x6 amps
    or 12 amps. 12 amps times 12 volts is 144 watts input power to the
    Vcore regulator circuit on the motherboard. The Vcore switching
    regulator, converts that power to a lower voltage. The converter
    might be 90% efficient. Therefore, I multiply by 0.90 and get
    144 * 0.9 = 129.6 watts, or rounding, about 130W of power available
    at the actual processor power pins.

    And that means, it is safe to connect a 130W processor, using
    only a 2x2 power connector.

    You should also check the CPU support chart, before sticking a 140W
    processor in the motherboard. Some VCore circuits don't support 140W
    processors. A motherboard could come with a 2x4 connector and a 95W
    Vcore circuit, for example. That would be lunacy, but for marketing
    reasons, the 2x4 connector may be used to fool people into thinking
    it is a "powerful" motherboard.

    OK, using this chart as an example, you can't even stick a 140W
    processor in that motherboard. The highest power processor is a 125W.
    The only way those extra pins on the connector would come in handy, is
    if you were doing an overclock of that 125W processor. At stock
    speeds, the 125W processor would be adequately handled by a 2x2 connector.

    http://www.gigabyte.com/support-downloads/cpu-support-popup.aspx?pid=3447

    I have heard of some cases recently, where there were malfunctions unless
    a 2x4 connector was used on certain motherboards. I haven't heard of an
    explanation yet, as to why that was necessary. Presumably, there is an
    issue with the motherboard design, but we can't go running around
    claiming "the sky is falling", when it clearly isn't. If you're using
    less than 130W of power, a 2x2 should be sufficient.

    My motherboard has a 2x4 connector and I'm using a 2x2 connector. So
    I'm not exactly in a state of panic :)

    Another thing to note about 2x4 connectors, is there is more than
    one wiring pattern for them. So don't grab just any supply, and attempt
    to use the 2x4 connector on it, without verifying it is the right type.

    For example, this article describes pinout of ATX GES type, which
    is quite different. And likely, a hard to find power supply.

    http://www.rackmount.com/rackacc/atxges.htm

    This article has more information about "regular" ATX wiring. If
    the ATX12V 2x4 connector has four identical yellow wires and
    four identical black wires, sitting in separate rows, chances are
    it is intended for your motherboard.

    http://www.playtool.com/pages/psuconnectors/connectors.html

    Paul
     
    Paul, Oct 8, 2010
    #2
    1. Advertisements

  3. Keiron

    Jan Alter Guest

    "Keiron" <> wrote in message
    news:tlGro.6$2...
    > Hi all, Just picked up a new motherboard (Gigabyte MA785GM-US2H) for a
    > low power system. I'm coupling it up with the Athlon 64 2000+ 8 Watt cpu,
    > so obviously only single core. I hadn't intended on upgrading the PSU
    > just yet but my current supply only has the 4 pin 12V connector (in
    > addition to the 24pin obviously). Now i've read that the 8 pin is
    > required for multiple cores so seeing as I'll be using a single core cpu
    > is itb fine just to use the 4pins or do I risk damage in some way? Thanks


    The 4 pin should continue to work just fine. Although I haven't come up
    personally with an 8 pin cpu power power connector I've read many reviews of
    purchasers on newegg.com using their old PS 4 pin connector on a new mb with
    an 8 pin connector and it working. The only thing I've read though is the
    additional 4 pins are supposed to support a more robust graphics display
    card rather than the additional cpu cores as you mentioned.
    You may want to check the manual of the mb to see what it says.
    Additionally, scroll down and read what 'NA' had to say in reference to the
    question you are asking about your mb...
    http://www.newegg.com/Product/Produ...k=False&VendorMark=&IsFeedbackTab=true&Page=4

    --
    Jan Alter
     
    Jan Alter, Oct 8, 2010
    #3
  4. Keiron

    philo Guest

    On 10/08/2010 11:25 AM, Jan Alter wrote:
    > "Keiron"<> wrote in message
    > news:tlGro.6$2...
    >> Hi all, Just picked up a new motherboard (Gigabyte MA785GM-US2H) for a
    >> low power system. I'm coupling it up with the Athlon 64 2000+ 8 Watt cpu,
    >> so obviously only single core. I hadn't intended on upgrading the PSU
    >> just yet but my current supply only has the 4 pin 12V connector (in
    >> addition to the 24pin obviously). Now i've read that the 8 pin is
    >> required for multiple cores so seeing as I'll be using a single core cpu
    >> is itb fine just to use the 4pins or do I risk damage in some way? Thanks

    >
    > The 4 pin should continue to work just fine. Although I haven't come up
    > personally with an 8 pin cpu power power connector I've read many reviews of
    > purchasers on newegg.com using their old PS 4 pin connector on a new mb with
    > an 8 pin connector and it working. The only thing I've read though is the
    > additional 4 pins are supposed to support a more robust graphics display
    > card rather than the additional cpu cores as you mentioned.
    > You may want to check the manual of the mb to see what it says.
    > Additionally, scroll down and read what 'NA' had to say in reference to the
    > question you are asking about your mb...
    > http://www.newegg.com/Product/Produ...k=False&VendorMark=&IsFeedbackTab=true&Page=4
    >



    The last machine I put together worked fine with the four pin PSU (in
    the 8 pin mobo)

    One word of caution: It's actually possible to mix up the additional 4
    pin connector with the *other* 4 pin connector typically used on P-IV
    mobos. They are not interchangeable...but the manufacturers stupidly
    made the keying all the same. I'm sure someone , somewhere has blown
    something up!
     
    philo, Oct 8, 2010
    #4
    1. Advertisements

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. NuQ
    Replies:
    7
    Views:
    506
  2. Mike Henley

    4 pin 12v atx power supply connected the wrong way...

    Mike Henley, Mar 31, 2004, in forum: Computer Hardware
    Replies:
    18
    Views:
    1,814
    Jon Danniken
    Apr 2, 2004
  3. BobTheCat
    Replies:
    3
    Views:
    273
  4. MachineMessiah

    1 x 4-pin ATX 12V Power connector = ....?

    MachineMessiah, Jul 5, 2007, in forum: Computer Hardware
    Replies:
    1
    Views:
    1,430
  5. Grinder

    8-pin vs 4-pin 12V connectors

    Grinder, Sep 10, 2009, in forum: Computer Hardware
    Replies:
    3
    Views:
    1,917
    Grinder
    Sep 10, 2009
Loading...

Share This Page