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PSU Form Factor Change?

Discussion in 'Hardware' started by hocuspocusblade, Jun 24, 2007.

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  1. hocuspocusblade

    hocuspocusblade Thread Starter

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    I have recently purchased an MSI KM3M-V socket A mobo which I have substituted in my eMachines W2260. The mobo was brand new albeit some 3 years old.

    I have tried two brand new PSU's on the mobo; one an Antec 350W and the other a Dynapower 500w, but neither of them will give me a video signal although they power up the HDD's, Floppy Drive, CPU & Fan.

    Out of curiosity I used the my old eMachines PSU, a Bestec 250w (not a wise move I'm aware), but that works just fine to the extent that I am using it to write this.

    My computer is around 4 years old and I am of the opinion that the PSU form factor must have changed over that time or is there something else I am overlooking here?

    Can anyone figure out what the problem is as I find it very difficult to believe that both brand new PSU's are DOA?
     
  2. JamesCo

    JamesCo

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    One way to test the new PSUs is to take a spliced wire (Do this at your own risk, if done properly nothing bad will happen) and put one end into the only Green connector that is on the 20 or 24 pin motherboard connector coming from the power supply. Then take the other end of that wire and connect it to any of the black corded connectors.

    [​IMG]

    If the fan in the PSU spins when you connect these then the power supply probably works.

    Also Check to see how many pins are on the mother board and how many pins are on the power supplies. When you connect the power supply do a few pins hang over the side?
     
  3. hocuspocusblade

    hocuspocusblade Thread Starter

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    The mobo is a 20 pin ATX and granted both the brand new PSU's I tried were 24 pin, but I disconnected the 'extra' 4 off each block before I plugged them in. I guess I just find it incredible that both PSU's are DOA, what's the chances of that happening as both were factory sealed in shrink wrap!
     
  4. win2kpro

    win2kpro

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    With Antec it would be pretty rare, with Dynapower not so rare.
     
  5. brite750

    brite750

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    nothing has changed with ATX, there is a new ATX2.0 but an Antec 350watt would be regular ATX, compare the plugs on the Bestec and the Antec they should be the same except for the extra 4pin block on the 20+4 pin ATX plug, also is there a 4pin pwr socket near the cpu socket, that needs to be plugged in also and your old MB may not have had that.
     
  6. brite750

    brite750

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    there is a 4pin pwr slot between your northbridge chip and the rear I/O panel, near a cluster of 3 caps, thats needs power
     
  7. brite750

    brite750

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  8. brite750

    brite750

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  9. hocuspocusblade

    hocuspocusblade Thread Starter

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    I have indeed plugged in the CPU 4 pin connector with each and every PSU I've tried, but the only one that works remains to be the original Bestec 250w! I am coming to the conclusion that yet again I've got another dead PSU!
     
  10. brite750

    brite750

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    :eek:
     
  11. JamesCo

    JamesCo

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    Did you try the test I suggested?
     
  12. hocuspocusblade

    hocuspocusblade Thread Starter

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    JamesCo...

    With a little bit of clarification from your goodself I shall conduct those tests this evening.
    I am aware that you short the green and black wires together, but do I need to have every other lead from the PSU plugged into the mobo? IE, how does the CPU fan get the power to turn?
     
  13. win2kpro

    win2kpro

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    Look at both NEW PSUs and see if you see a single white wire on the plug that connects to the board. The white wire is a -5v wire and is not now used on current motherboards. The specs for the Antec and Dynapower PSUs indicate that there is no -5v present.

    Now look at the old Bestec and see if you see a single white wire connected to the plug that connects to the board.

    If so, the Bestec still probably has an operational -5v lead, and it is POSSIBLE since this is an older board that it needs the -5v to function.
     
  14. hocuspocusblade

    hocuspocusblade Thread Starter

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    I shall investigate that now and it seems a distinct possibility. In the meantime, perhaps more food for thought...
    Previous to testing out the Bestec on the mobo I also tried a Hitec 175w microATX PSU from an 5 year old HP 520W Pavilion and that worked just fine too!
     
  15. hocuspocusblade

    hocuspocusblade Thread Starter

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    The results are in...
    Right, the Antec has no white wire, the Dynapower does have a white wire and the Bestec also has a white wire too. I haven't checked the HP 520w PSU as wifey is currently playing a game and she is winning, LMAO!
    So, I conclude from that that the mobo does require a PSU with a white wire (whatever that is for) and the reason the Dynapower has it but doesn't work is because that is truly DOA, yes?
     
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