Mac Pro 100% cpu core usage

Discussion in 'Mac Pro' started by kingofclubs, Oct 7, 2010.

  1. kingofclubs macrumors newbie

    Oct 7, 2010
    Hello all,

    I'm new to the forum, and already have a question about some troubles I've been having with my Mac Pro.
    It's a 2008 2.8Ghz 8-core with 256MB graphics card and 6GB or RAM, with latest version of Snow Leopard 10.6.4 and most recent browser updates.


    Now, when I bought this Mac Pro second hand, it came with only 2GB RAM (2x 1GB) and I added another 4GB myself (2x 2GB). This was a few months ago.

    However since a few weeks, I've been having issues with my CPU usage, mainly in Safari or any other web browser, especially when streaming video. After a few minutes, 10 max., the CPU usage in one core shoots up to 90 or 100% and the other 7 remain idle and unused. I tried this in Safari as well as Firefox, both with the same result.


    This results in serious video lag, and browser slowing down significantly in general. This happens even when there are no other applications opened, besides perhaps Mail. When working in Photoshop or Illustrator or any other graphically heavy program, the CPU usage is distributed much more evenly across all 8 cores and all seems to be fine, so I don't think it's a graphics problem.

    Now I went to look into my System Profiler and noticed that one of the 2GB RAMs I installed shows an ECC Error.


    I had this ECC Error right after installing the DIMMs, but it disappeared after a day or so and I didn't really bother to look at it again until recently. Also video streaming went wonderfully for a few months, streaming 1080p with barely a hitch.

    Could this ECC Error on the DIMM be the problem? Or has anyone had a similar issue with their Mac Pro and video in browsers? If so, how did you solve it?

    Any help or ideas regarding this issue would be greatly appreciated.
  2. Queso macrumors G4

    Mar 4, 2006
  3. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    Open Activity Monitor > From the top of the window select ALL PROCESSES > Sort processes by CPU usage > Post a screenshot (or tell what process is taking so much CPU power)

    That sounds like a software glitch
  4. pastrychef macrumors 601


    Sep 15, 2006
    New York City, NY
    If you are getting ECC errors with your RAM, contact the place where you bought it from for an exchange. It's bad RAM.
  5. kingofclubs thread starter macrumors newbie

    Oct 7, 2010
    Thanks for the advice, this did the trick!

    As for the ECC Error, I think I will be contacting the seller for a replacement.
  6. kingofclubs thread starter macrumors newbie

    Oct 7, 2010
    Okay, for some reason, now that my browser problem is solved, something has changed:

    Instead of the usual 6GB of RAM, now my system profiler tells me I have only 4GB of RAM installed. And this without any physical changes to the Mac Pro whatsoever.

    I had the problem of the 2GB DIMMs being read as 1GB when installing them, but that was due to placing them in the wrong order and had that fixed after a while. Now, after the Flash Plugin update, all of a sudden the 2GB DIMMs are -again- read as 1GB. How the *** is this possible? I didn't touch any of the DIMMs, didn't even open the computer!

    Any ideas on this? I'm really puzzled here, and I need all the RAM I can get for my graphic work.
  7. SkyNite macrumors member

    Sep 21, 2010
    Perhaps that 2 GB DIMM with the ECC errors has been disabled because of those errors.
  8. kingofclubs thread starter macrumors newbie

    Oct 7, 2010
    I thought of that too, but what about the other 2GB DIMM that never showed an ECC error? It shows in System Profiler as 4x 1GB:

  9. SkyNite macrumors member

    Sep 21, 2010
    While it does appear strange in System Profiler, I have seen bad RAM sticks cause flaky reports and generally odd behavior. Hopefully your replacement RAM will solve it.

    And it never hurts to reset the PRAM.

Share This Page