Are these symptoms of a Bad Power Supply?

Posted on 2006-04-05
Last Modified: 2011-08-18
A friend just built a new PC, and is having some trouble...

sometimes windows goes into a boot loop. sometimes windows boots perfectly.  most recently, he flipped the power switch and the LEDs on the fans flashed briefly and then NOTHING.  then after 2 or 3 tries, booted normally into windows.

Does this sound like a bad Power supply? Bad Memory? Motherboard? CPU?
Question by:fruhj
    LVL 44

    Accepted Solution

    first and easiest is to test memory.  If it is CL3, and the chipset is NVidia, or any modern fast chipset, the RAM is too slow for the motherboard.  Needs to be changed.  PS is easy to test, just try another for 2-3 boots, and when you find no change, go to RAM first, if a change, leave PS in and continue running.  It is unlikely these symptoms are bad CPU, could be a fan too slow, but easy to test at BIOS level, just boot to BIOS, monitor PC Health for 20 mins, if temp stable at around 24-28C, CPU fan is fine.  As for bad MB, that is difficult to test, need to make sure RAM is fast enough first, and PS is functional to ful voltage.  In summary, RAM with too slow a CL refresh is most likely culprit.
    LVL 14

    Assisted Solution

    Could be an inadequate power supply, evaluate here:
    LVL 8

    Assisted Solution

    The boot loop sounds like RAM. The inability to boot at all sounds like a power supply.

    To test the RAM, I recommend something like MemTest86+ ( Let it run all the way through at least once. If you get lots of errors, the bad memory is definitely going to cause major problems. If you get a few errors the memory would probably be causing intermittent problems (especially if they're all in test #5).

    LVL 44

    Expert Comment

    Memory testing programs only test the Rams ability to write and read data, they do not compare the RAM latency speed against the latency requirements of the motherboard (i.e. they can come up with a result that the RAM "is fine", when it is inadequate for the latency requirements of the motherboard chipset.
    LVL 2

    Assisted Solution

    If you would like to test some more deep into the comp resources try Ultimate boot cd
    LVL 91

    Assisted Solution

    you can diagnose by disconnecting devices, or starting with the minimum :
    mobo + cpu +1 ram stick, 1 disk, video card, keyb and mouse.
    if still the same, try without keyb and mouse.
    Most probable is the motherboard .
    LVL 2

    Assisted Solution

    Bad PSU's are quite rare, if the fan works at the back they're generally OK - its worth checking the output is sufficient though.   Check to see if the P1 connector is fully pushed in to the motherboard, and any auxiliary power connectors are seated properly.  Check to see if the other peripherals and cards have been seated properly, and the relevant screws are in place.
    LVL 12

    Author Comment

    Thanks everyone for your feedback on this!

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