Imac Pro not as powerful as expected

Discussion in 'iMac' started by vessel131, Jun 15, 2018.

  1. vessel131 macrumors newbie

    Jun 15, 2018
    First time post, so please forgive me if this is in the wrong sub or if I need to supply more detailed information.

    I recently bought one of the stock model Imac Pro (3.2 GHz, 8 core etc) as a hasty replacement for a self-built machine which suffered a boot drive failure.

    The Imac is a slight climb down in specs from my last machine which had a 3.5 GHz CPU and the same amount of RAM, 32 Gb.

    The only thing I use these machines for is making music, and to say there is a difference in performance doesn't even come close to what is happening. I am seeing huge CPU spikes in Ableton, Bitwig and Logic when working opening one instance of a plugin or instrument, and I typically use these machines in a very intensive way, hence investing in one with (on paper) pretty good specs. The fans are running fairly hard upon opening any of these programs and the computer heats up pretty quickly. Something just doesn't feel right. I've got activity monitor running and there don't seem to be any background processes eating into my CUP resources, but that's exactly what it feels like.

    Any suggestions or advice regarding solutions to this problem would be greatly appreciated. I'm pretty astonished that a machine this expensive is acting like this.

    Many thanks
  2. Silencio macrumors 68020


    Jul 18, 2002
    Exactly which 3.5GHz CPU did your old machine have? Clock speed alone doesn't really say much.

    Did you clean install your apps on your iMac Pro, or did you attempt to migrate your apps from a previous system?
  3. chrfr macrumors 604

    Jul 11, 2009
    This is not indicative of a performance problem at all. Are the applications actually performing like they should?
    The iMac form factor does not have the large cooling space that a tower style computer has, so it should be expected that the fans will speed up when the computer is under load.
  4. BayouTiger macrumors 6502


    Jul 24, 2008
    New Orleans
    Something definitely wrong. I can hammer my base iMP for hours and while the fans might spin up, I can rarely hear them and I would never describe the machine as very hot. I can't even imagine a situation where opening any program would tax the machine.
  5. ColdCase macrumors 68030

    Feb 10, 2008
    OP says activity monitor is showing huge spikes in CPU use, which will cause the fans to spin up, eventually. Mine does

    How many cores did the old 3.5 GHz machine have?

    Did the old machine have the same OS, i.e. does the apps need to be updated to work well with High Sierra?

    You may want to try a fresh install of the apps as another has suggested.
  6. rjsounds macrumors member


    Jul 3, 2017
    Yes, but not usually from music production, especially an iMac pro with better heat management than the regular iMacs. I can run fairly large Logic Pro X orchestral projects (over 100 tracks) on my 2017 i7 iMac and still not even use half the CPUs processing power. I think there's something up with his machine.

    The OP was stating that activity monitor DOESN'T show anything too strenuous on the CPU, which is odd considering it definitely sounds like something is taxing it pretty hard.


    OP: In Logic or the other DAWs, when you double click on CPU meter, it will show the number of cores, right? Is it showing one, or all cores being strained? The reason I ask is I was experiencing a similar issue with Logic somehow maxing out one core, which oddly had something to due with airport at the end of the day. If you disable airport and re-enable airport does it make a difference? Do the CPU spikes stop? How long after opening up your DAWs do the fans ramp up? Is it when you do something specific? Does it happen when you open other programs?

    P.S. If your issue sounds similar to mine (mind you this was 5 years ago), you can look at the thread posted on LogicProHelp forums:
  7. joema2 macrumors 68000


    Sep 3, 2013
    He said "upon opening" his apps, his iMac Pro heats up pretty quickly. That is not normal for an iMac Pro. A CPU *spike* will not cause high fan noise on an iMac Pro. By contrast *sustained* high CPU coupled with sustained high GPU activity might eventually cause fan noise on the iMP but it won't happen quickly upon launching the apps.

    I can transcode video for long periods at very high CPU levels without my iMac Pro fans getting loud.

    On my 2017 i7 iMac 27, if I run the "yes" stress test the fans spin up audibly with 30 seconds. On my 10-core Vega 64 iMac Pro I can run this on all cores for long periods (apparently forever) without them spinning up:

    When you say "yours does", what iMac Pro do you mean?
  8. joema2 macrumors 68000


    Sep 3, 2013
    To be sure, I just ran this test on my 10-core Vega64 iMac pro for over two hours. After 10 minutes the fans increased from 1100 to 1650 rpm. Two hours later they were still at about 1650 rpm yet all CPU cores were pegged. The fans were never really audible above the sound of the RAID arrays on my desk. By contrast on my 2017 i7 iMac 27, I could hear the fans after 30 seconds. By 45 seconds the fans on the iMac were at 2700 rpm.

    There is a gigantic difference in cooling and acoustic behavior between the iMac and iMac Pro. All the comments about the iMac form factor having poor cooling are uninformed. The iMac Pro has exactly the same form factor as the iMac yet it has excellent cooling.
  9. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark

    I'd like to add that when I edit video on my 5K iMac (2014) or play games, I often can get the fan speed as high as 3600RPM. Typically 3200, but 3600 has happened a fair few times.
  10. ColdCase macrumors 68030

    Feb 10, 2008
    Recent iMac Pro 10 core Vega 64

    When I run handbrake on some videos transcodes, activity monitor indicates 1800- 1900 % and within 10- 20 seconds the fans are quite noticeable. After 30 minutes even more noise. This is routine.

    Some Compressor transcode jobs also indicate 1800-1900% and those spin up the fans eventually.

    Jobs less than ~1700% CPU indicated heat up the iMac but I don't notice fans spin noise (There is quite a bit more hot airflow than idle, however).

    The OP said the CPU spiked when using specified apps, and by the tone of the rest of his post I assumed that to be an extended sustained spike. Others seem to assume differently. Perhaps the OP can clarify so we all can get on the same page.
  11. Hater macrumors 6502a


    Sep 20, 2017
    Edinburgh, Scotland
    You spent 5 grand on a machine slower than your current one because a $150 hard drive failed?

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10 June 15, 2018