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PSU missing 12v 4-pin connector 4 CPU power supply

Discussion in 'Motherboards' started by TJ Sackville-West, Dec 15, 2004.

  1. Suggestions please to rig power for the square 4-pin 12v connection,
    missing from the cabling from a CODEGEN 250X-1 250W PSU

    Have an MSI KM3M-V mATX board which has the square JPW1 (4-pin 12v)
    connector to power the CPU. 2x GND & 2x 12v pins showing.

    I don't know why this ATX PSU unit which is only 4-5 years old doesn't
    have the square pin for the CPU power supply. Maybe is too old and the
    new generation of CPU need direct higher power supply that the 20-pin
    socket can provide, but I'm only putting on a Sempron 2400 so I should
    be able to tap off 12V from somewhere and run it in with the correct
    male fitting.

    Thanks
    TJ
     
    TJ Sackville-West, Dec 15, 2004
    #1
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  2. TJ Sackville-West

    Wes Newell Guest

    Get an adapter cable from Molex to the 12v connector.
    The 4 pin 12v connector was introduced with the P4, after your PSu was
    built. BTW, AMD recommends a 300W PSU minimum for the K7 line. But I've
    run a couple on 250W nits.
     
    Wes Newell, Dec 15, 2004
    #2
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  3. TJ Sackville-West

    Adam Guest

    I was under the impression that the additional connector not only
    provided more power but isolated power and ground planes for the CPU.

    --adam
     
    Adam, Dec 15, 2004
    #3
  4. TJ Sackville-West

    Noozer Guest

    Mr Troll... 4-5 years makes it an antique as computer parts go.

    If it is a 250watt PSU then it won't have enough juice to run the system
    anyhow.

    If you want a modern computer, bite the bullet and buy a modern PSU.
     
    Noozer, Dec 15, 2004
    #4
  5. TJ Sackville-West

    kony Guest


    I don't think it isolates ground and power might depend on
    the board. Some past boards would potentially run, albeit
    with the potential for instability, with only the 20-pin
    connector attached. Other boards won't, definitely must
    have 12 in at the 4 pin connector.
     
    kony, Dec 15, 2004
    #5
  6. TJ Sackville-West

    kony Guest


    A 4-5 year old Codgen 250W isn't suited for this system.
    Granted a Sempron 2400 isn't as demanding as some, but the
    age of the PSU combined with it's generic low-quality
    nature, lower capacity to begin with not even considering
    that it may be optimized for amperage mostly from the 5V
    rail, not 12V rail, might be too much for the old Codegen
    which wasn't a very good PSU even when used in systems
    contemporary at the time.

    You can get an adapter that plugs into a 4 pin molex
    connector but you'd be better off getting a new ~ 350W
    name-brand power supply.
     
    kony, Dec 15, 2004
    #6
  7. TJ Sackville-West

    Wes Newell Guest

    What the board does with it depends on the board, but as far as the PSU is
    concerned, it's just another 12v line coming from the same place as the
    other 12v lines. Having the extra cinnector makes sure there's enough
    copper for the load of the CPU.
     
    Wes Newell, Dec 15, 2004
    #7
  8. TJ Sackville-West

    kony Guest


    True it's often just another lead from the same 12V rail
    (ignoring newer split-rail designs) BUT with the switch to
    ATX 2.03 some may also have shifted to more 12V current
    bias. In other words, typical 200-250W PSU bought today
    might be much more suitable for powering a (12V based VRM
    circuit) than an old PSU.

    Granted the label is "supposed" to help guide on in these
    choices but then we're back to the same timless argument
    about whether one can trust the label on any particular
    generic power supply.
     
    kony, Dec 15, 2004
    #8
  9. TJ Sackville-West

    TJ Guest

    Thanks for the advice.I bought a 400W PSU. Started up OK first time

    - Tuff Test lite shows all VGA OK - only problem is Windows 98 won't
    boot from the drive I had before.

    Tried another HDD and that won't boot either.

    Even tried booting from the CD ROM to install Sus Linux 9 and that
    seemed to go into a void too

    Is there some kind of a test probgam I can download to run from either
    CD or floppie to check the board in DOS?

    Thanks

    TJ
     
    TJ, Dec 19, 2004
    #9
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