voltages on PSU

By Tedster ยท 8 replies
Jul 30, 2006
  1. I'm getting the following for voltages on my voltmeter: 11.66 on 12V rail, 5.08v on 5v rail,and 3.27 on 3.5v rail for my PSU. Is this good?

    It's a generic 600W PSU.
  2. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Nothing to worry about there mate.

    + or _ 5% variation of the voltages is acceptable. Your voltages are well within that range. The amount of amps delivered on the 12volt rail is something you should take a look at. The info should be on the psu label.

    Regards Howard :)
  3. iss

    iss TechSpot Chancellor Posts: 1,994

    I agree with howard the voltages look fine.
  4. Tedster

    Tedster Techspot old timer..... Topic Starter Posts: 6,002   +15

    thanks. I'll test the amps and let you know.

    I noticed the 3.5 rail is a hair under voltage. I'll retest.
  5. i_am_a_newbie

    i_am_a_newbie TS Rookie Posts: 170

    you mean the 3.3V rail?
  6. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Well spotted mate lol. It it is indeed a 3.3volt rail and not 3.5volts.

    Regards Howard :)
  7. KingCody

    KingCody TS Evangelist Posts: 992   +8

    the ATX specification states that +/-5% is acceptable (as howard already mentioned)

    but even cheap PSUs will often have good voltage readings when idle, but they will often fluctuate more than +/-5% when taxed. and since it's a "generic 600w", it will probably become taxed at around 350w~400w.

    I am guessing that you read those voltages at idle or low-load? if those readings were under full load then you got very lucky with a "good generic" (nice oxymoron... hehe :p )

    cheers :wave:
  8. Tedster

    Tedster Techspot old timer..... Topic Starter Posts: 6,002   +15

    I did a PSU calculator and with all my gear to include lights etc (which I don't use and turn off), my wattage requirements come out to about 300W.

    So I think I have plenty of headroom on the PSU. I'm returning my burned out graphics card for replacement. I'm debating whether or not to replace the PSU. The voltages appear ok under idle.
    I have no way to test under load as the graphics card is dead.
  9. KingCody

    KingCody TS Evangelist Posts: 992   +8

    300w is an average requirement for a modern system. (add 100w extra for dual video card systems). but the total wattage rating on a PSU is pretty much useless because it's what makes up that wattage that's important.

    socket-A (which I believe is what you have) and all newer platforms rely heavily on the +12v rail. did the PSU calculator give a +12v amperage requirement?
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