New mac pro slight buzz from psu. Is this normal?

Discussion in 'Mac Pro' started by nigel1210, Mar 24, 2009.

  1. nigel1210 macrumors member

    Joined:
    Mar 24, 2009
    #1
    Just received a nehalem mac and there is a slight buzzing noise coming from the psu.

    You can only really hear it when you go close to the back of the mac pro.

    Is this normal?
     
  2. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #2
    It can be, but a better PSU won't. I'm not sure about the new MP's, but I think they may be using the same PSU from the '08 model.

    By chance do you have access to a UPS or a Line Conditioner?
    If so, plug the computer into one of those, and see if the hum dissappears (A/C hum, due to poor power quality).
     
  3. Tallest Skil macrumors P6

    Tallest Skil

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    Aug 13, 2006
    Location:
    1 Geostationary Tower Plaza
    #3
    It's a different PSU; they're in the high eighties on the efficiency scale as opposed to the one in the aught eight Mac Pros.
     
  4. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #4
    :cool:

    Where did you spot this information?
     
  5. Tallest Skil macrumors P6

    Tallest Skil

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    Aug 13, 2006
    Location:
    1 Geostationary Tower Plaza
    #5
  6. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #6
    :cool: Thanks for the link. :)

    You do realize, that's peak efficiency though. ;) No PSU holds the same efficiency across the entire load. It's a curve. :p Efficiency usually peaks somewhere in the ~500 - 750W range, depending on the design. ;)
     
  7. belvdr macrumors 603

    Joined:
    Aug 15, 2005
    #7
    I always heard that any power supply is at its most efficient during a full load. Never tested though, because I never cared. :)
     
  8. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #8
    Not quite, but close. ;) About 65 - 75% of full load. :) Efficiency dumps after that. Not quite so wonderful before either. :p
     
  9. nigel1210 thread starter macrumors member

    Joined:
    Mar 24, 2009
    #9
    There swapping it out anyway.

    Wonder if the replacement will still be the same.
     
  10. Infrared macrumors 68000

    Infrared

    Joined:
    Mar 28, 2007
    #10
    Yes. There's nothing to worry about. Apple use the best quality bees.
     
  11. jjahshik32 macrumors 603

    Joined:
    Sep 4, 2006
  12. soldierblue macrumors 6502

    Joined:
    Mar 23, 2009
    #12
    Yeah, totally normal. I had a chat with PC Power and Cooling about just this a few weeks ago. Normal fluctuations in the power draw of the system can cause the coils to vibrate or capacitors to whine.
     
  13. nigel1210 thread starter macrumors member

    Joined:
    Mar 24, 2009
    #13
    lol@infrared

    This is weird as my pc psu doesn't do it at all, and their plugged into the same Surge strip.
     
  14. soldierblue macrumors 6502

    Joined:
    Mar 23, 2009
    #14
    Some brands tend to do it, some don't. Seasonic is a particular offender, they're the OEM for Corsair and PCP&C among others. Maybe the same OEM manufactured these?
     

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