PM8M Mobo w/ New PSU wont boot

By wstevens ยท 5 replies
May 11, 2009
  1. I have a pm8m with a new 500w atx PSU and when i connect the 4 pin for the cpu the fan only twitches and when i remove it, everything else powers up.any suggestions?

    thanks in advance

  2. dmill89

    dmill89 TS Guru Posts: 475

    The fan twiches. Does anything else happen? What is the brand/model of the psu? What are the system specs? How many amps are on the various psu rails (on the label)?
  3. mailpup

    mailpup TS Special Forces Posts: 7,188   +470

    Make sure you are using the correct 4 pin connector. Your motherboard uses a 20 pin main power connector. Most power supplies come with a detachable 4 pin connector for use with a more modern 24 pin motherboard. This 4 pin is not the same as the ATX 12V 4 pin connector you are supposed to be using for the CPU. I only mention this in case you got them mixed up.
  4. wstevens

    wstevens TS Rookie Topic Starter

    it is a switching Power Supply
    Model: ATX-110/220v 500W-PIV
    current 8A
    Frequency 50-60 hz

    My System is an
    Intel Pentium 4
    MSI PM8M Board
    512 mb DDR
    Windows XP SP2

    Do i need to get another power supply?
  5. mailpup

    mailpup TS Special Forces Posts: 7,188   +470

    The information you need to get from your power supply is not on the back of it. You have to open the case and look for a sticker on the side of the PSU with the amperage information.
  6. dmill89

    dmill89 TS Guru Posts: 475

    There should be a sticker on the side or bottom of the psu with a chart listing voltages and amps ex: 12v/30A, 5V/20A,etc. or in boxes such as 12v in one box and 30A in the box below, 5v in the box next to 12v, and 20A below it, etc.. (it may not be 30 or 20A I was just useing those as an example).The label should also list the manufacture or at least the brand of the PSU (some are better then others if there is a ul number [a backwards UR symbol with a number under it] this may lead to the actual OEM). This information is importent since not all PSU's are created equall. Infact many cheaper 500w PSU's actually only output around 200w. Since the psu is new it is suspect but might not necessarily be the cause. By the way why did you install a new PSU? If you still have the old one and it is working try it and see if it eliminates the problem, If you replaced the old PSU because it failed it may have taken other hardware with it. and as mailpup said the 4 pin P4 connector is not connected to the 20 pin main and should have 2 yellow and 2 black wires as well as it's owin clip for secureing it to the motherboard.
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