4 Replies Latest reply on Jul 19, 2014 10:42 AM by Arivl

    12 core Mac Pro does not improve render time over iMac quad core


      I'm rendering the same composition independently on two computers and they are basically rendering at the same rate, which is slightly better than 1 frame per second.


      The project settings and preferences are identical in each instance (with the exception of memory and multiprocessing, which I have experimented with ad nauseum). The composition includes no motion blur, no effects, just a couple of layers of chroma keyed .mov files (using keylight 2.0) and some still images. Neither machine is running any other applications, except occasionally Google Chrome, which seems to have no effect on performance.


      Both systems are running the latest version of After Effects CC (2014) and using the Classic 3D renderer.


      System 1 MAC PRO:

      • Mac Pro 12 core 2.7 GHz Intel Xeon E5
      • dual AMD FirePro 500D 3072 MB GPUs
      • 32 GB RAM
      • OS X 10.9.4

      System 2 iMAC:

      • iMac quad core 2.5 GHz Intel Core i5
      • AMD Radeon HD 6750M 512 MB GPU
      • 8 GB RAM
      • OS X 10.9.3


      As you can see, system 1 is vastly more powerful, and yet no combination of memory/multiprocessing settings can get the system to render faster than system 2.


      It doesn't seem to matter how much or little RAM I reserve for other applications (I have settled on 4 GB), or the number of CPUs I reserve for After Effects. The one setting that has improved performance is turning OFF render multiple frames. And even then it only brings the performance of the Mac Pro up to par with the iMac. I have cleared my cache, rebooted the computer, and read everything I can find online regarding the optimization of render settings.


      Here's a comparison of the respective CPU Loads:



      iMac CPU Load.jpg

      Mac Pro

      CPU load.jpg

      With such a low CPU load, After Effects is obviously not utilizing the resources available to it on the Mac Pro. What a waste.


      Can anyone help?

        • 1. Re: 12 core Mac Pro does not improve render time over iMac quad core
          Arivl Level 1

          For a start, I don't think you have a sufficient amount of ram to utilize all the processors, so it's not surprising that the processors aren't the bottleneck.   I would check to see if your ram is being completely tapped out during the render, and if so, it would explain why you aren't seeing your CPU being fully utilized.


          For reference, I have a Mac Pro with 8 cores, and 128GB of ram, and under many circumstances AE uses all of it.

          • 2. Re: 12 core Mac Pro does not improve render time over iMac quad core
            oliverwatson Level 1

            Thanks for the response, Arivl. I'm sure you're right about the mismatch of RAM and processors, but it still doesn't explain why it isn't outperforming a machine with one quarter the RAM. Shouldn't it be at least twice as fast as the iMac if I allocate 8 cores and 16 GB of RAM, versus the maximum 4 cores and 8 GB available on the iMac?

            • 3. Re: 12 core Mac Pro does not improve render time over iMac quad core
              Andrew Yoole MVP & Adobe Community Professional

              There's plenty of debate about the new Mac Pro vs a kitted out iMac.  Benchmarks show that some iMac After Effects processing can actually be faster than on a Mac Pro, depending on the content and some other factors.  If you're using software that has been optimised for the Mac Pro's GPU-centric architecture, like Final Cut Pro X, you will see great benefits.


              mac pro vs imac


              In my own facility recently we opted out of purchasing Mac Pros this year, and bought top-end iMacs instead.  The benefit to cost ratio simply didn't make sense for us right now.  Mac Pros are awesome machines, but a significant component of their cost is the dual GPUs, which are simply no benefit to After Effects.


              Reports say that the After Effects engineers are working on a major revamp of the After Effects processing system, so I'm betting you will realise far greater benefits from your Mac pro in coming AE versions.  For now, you may continue to see performance that is not spectacularly better than a souped-up iMac, depending on the type of processing involved.


              I've seen a few benchmarks that suggest the 8 core systems give better bang-for-buck than the 12 cores.  Try reducing your processors to 8 in After Effects and see if it makes a difference.  With 8 cores, allocate 3GB of RAM per core to leave some RAM for the OS.

              • 4. Re: 12 core Mac Pro does not improve render time over iMac quad core
                Arivl Level 1

                Oliver, you're right in principle that more ram should enable you to use more processors, but the truth is that AE often is unable to hand multiprocessing efficiently.   As you know, depending on the project, it's sometimes better to have multiprocessing disabled entirely, but even in those situations where it lends some advantage, it might still not be better than having fewer, faster processors.


                If you post a link to a collected test project and your render times (both nMP and iMac), I can try rendering it on my system to see where the bottleneck is.