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Nehalem Mac Pros suffering audio-based performance hits

updated 10:05 am EST, Wed February 3, 2010

Spikes in power, heat

The current Nehalem-based version of the Mac Pro, released in October 2009, is being impacted by unusual performance problems, owners say. Certain audio tasks -- ranging from playing music in iTunes, to using USB or FireWire interfaces -- may cause performance to drop by as much as 20 percent in other areas. CPU power consumption can multiply by several orders and generate twice the normal amount of heat.

The problems are believed to be connected to Mac OS X, as booting into Windows 7 on a Mac Pro eliminates any issues. Based on testing it is suspected that there could be a flaw in OS X's handling of power management kernel extensions, or else the driver that exploits particular Nehalem features, such as SpeedStep and Turbo Boost. Apple has not commented publicly on the matter however, and so it is unclear where the precise fault lies.

AppleCare technicians are reported to have dismissed user complaints in a number of situations. The company should nevertheless be aware of audio issues, as one case is said to have been forwarded to engineers at Apple's Cupertino headquarters. Problems with iMacs may be taking a higher priority.




by MacNN Staff

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Comments

  1. danviento

    Joined: Dec 1969

    0

    Post Further Developments, Plz

    As someone who's in the market for a used Mac Pro to do Audio production work with Logic Studio, I'd like to know if these issues are known for this area of audio, as the Headline seems to imply. If we get word on an OS update that fixes it, that'd be nice to know too.

  1. testudo

    Joined: Dec 1969

    0

    Re: Post

    From all that I've read, the internal audio components cause the computer to run at high-CPU, which also ranks up the fans due to the heat generation. Doesn't matter what you're doing with audio, or how it is playing.

    The workaround (from what I gather) is to get your own Audio card and place it in there, which I assume works because it is using it's own audio drivers, not the ones for the built-in audio devices.

  1. Tralthamidor

    Joined: Dec 1969

    +6

    No problem here

    We have 2 of the new 8 core Nehalem Mac Pros and are using Logic 9.1 with firewire MOTUs. I am not experiencing these problems and we push them pretty hard. Certainly not noticing any heat problems.

  1. brtheribid

    Joined: Dec 1969

    +3

    Problems here too

    I traded in my dual 1.8 G5 tower for a 2009 quad Nahalem. I was surprised that iTunes songs would often stutter before playing. Worse than that, I used to get at least 10-14 tracks with automation out of Garageband 2.0.2 in Tiger without a hiccup, midi and real, with more than a few effects on many tracks, (and without converting), with no problem. (Had 1.25 gig of RAM then) Was surprised to find that a simple project with only a few tracks and volume automation choked the new Garageband with 3 gigs of ram in Leopard.
    Hoping for a fix soon!

  1. brtheribid

    Joined: Dec 1969

    -3

    Problems here too

    I traded in my dual 1.8 G5 tower for a 2009 quad Nahalem. I was surprised that iTunes songs would often stutter before playing. Worse than that, I used to get at least 10-14 tracks with automation out of Garageband 2.0.2 in Tiger without a hiccup, midi and real, with more than a few effects on many tracks, (and without converting), with no problem. (Had 1.25 gig of RAM then) Was surprised to find that a simple project with only a few tracks and volume automation choked the new Garageband with 3 gigs of ram in Leopard.
    Hoping for a fix soon!

  1. WalkTheTalk

    Joined: Dec 1969

    +3

    Yes there are issues!

    I have been in talks with Apple tech support for weeks on the same case : USB slowness. There are still many test to be done but I can say I did install a USB PCI-e card and that did not fix the problem.. and Apple is working on it. I even put the hard disks on the PCI-e card and separated the USB 1.0 devices from the 2.0 devices.. Keep on calling and posting!

  1. testudo

    Joined: Dec 1969

    -3

    Re: No problems here

    We have 2 of the new 8 core Nehalem Mac Pros and are using Logic 9.1 with firewire MOTUs. I am not experiencing these problems and we push them pretty hard. Certainly not noticing any heat problems.

    But you're using third-party audio cards. Which kind of points to the problem being with the built-in hardware and getting a third-party card is a workaround (albeit not a cheap one).

  1. Fast iBook

    Joined: Dec 1969

    -2

    My iSub...

    My iSub from 2001 has USB issues with my pmac from 2002 running 10.4. Apple has always had c*** audio support with USB in osx, they want you to buy optical stuff, or use the audio out mini-jack. The USB stuff in OSX is very weird i'll say that for sure. Never had one single issue with FW.

    - A

  1. bxs

    Joined: Dec 1969

    0

    Hmmm -- a performance hit of 20% is bogus IMO

    Sure thing -- but I don't understand what all the fuss is about.

    My Mac Pro when at idle will have its 4 cores at around 137 deg F. With an ambient temp of around 84 deg F when playing iTunes music it's typical for all 4 cores to kick up to 165 deg F. So what? This isn't an issue and the CPU does not overheat and my Exhaust, Intake and Power supply fans hover at their idle speed of 600 RPM. The Booster and Fan expansion slot fans hover around their idle speeds of around 800 to 850 RPM.

    The Marcel Bresink's Hardware monitor shows an Upper Limit for the core temps to be 212 deg F.

    CPU's do get hot when used -- that's all I can say.

    I do not see this as an issue on my 2.66 GHz Mac Pro 4-core Nehalem.

    [Edit]

    My idle power consumption sits at around 145 watts and when iTunes is playing music it kicks up to around 217 watts. This translates to around 246 BTU/hour.

    I guess the question being asked is -- Is the rise in CPU temp and power increase warranted for the likes of iTunes playing a music file? I dunno!

    What I can tell you is that if I run all 8 core threads at 100% cpu while iTunes is playing a music file the core temps will all kick up to around 207 deg F and power consumption runs at around 270 watts and fans ramp up another 100 RPM from idle speeds.

    If I now pause the audio from iTunes the core temps and power draw remain at the levels of 207 deg F and 270 watts.

    Again, the CPUs can run very hot but the Mac Pro's cooling system handles it very well and with little to no discernible noise.

  1. emig647

    Joined: Dec 1969

    +1

    What's really going on...

    ... this has been known for months now. There isn't a 20% speed decrease, it's that the cpus doing do a 20% speed increase (known as speedstep on nehalem).

    Also, it isn't the temp of the cpu's that are increasing so much as the northbridge. The northbridge temp goes bonkers as soon as audio starts getting processed. I also have tried other apps (songbird) besides itunes / quicktime to verify it wasn't CoreAudio. They all do it.

    I expect to be fixed by the time the next Mac Pro comes out as it will have the same northbridge driver set.

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