I introduce myself, my name is Kepa and it's my first message in the forum, I wanted to ask for help with a problem that I have when it comes to rendering via CPU. I attached image, of what I comment. As I commented the problem arises when I render through CPU, I have a workstation with a Dual Xeon 2699 V3-72 Processing threads, when I shoot render in Blender does not use more than 20%, as you will see in the attached image I had to correct it inside Of the performance section of the render tab, the auto threads detected by default puts me 36, that is half of them, I put 72 and nothing, is useless. I do not know if it is due to a Blender problem or that, I work under Max and with the rendering engine works 100% CPU I understand that it is Blender problem. Any help would be appreciated. enter image description here

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    $\begingroup$ Related: blender.stackexchange.com/questions/16251/… $\endgroup$
    – brockmann
    Jul 11, 2017 at 9:46
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    $\begingroup$ My guess is that the scene is not complex enough to push the CPU to the max, maybe increasing the tile size will have an effect in that direction $\endgroup$
    – user1853
    Jul 11, 2017 at 11:07
  • $\begingroup$ Maybe Blender is not well optimized under Xeon processor and can't fully detect/take advantage of the hardware available $\endgroup$ Jul 11, 2017 at 17:44

2 Answers 2


From your screenshot, you can see that you are only rendering 12 tiles. If you have 72 hyperthreads, then 12 tiles / 72 threads ~= 16% utilisation. Options:

  • Render the full image, instead of small fraction that you are.

    enter image description here

  • Reduce the render tile size so that you have more tiles rendering at once.

    enter image description here


I had the same question and later realized that the graphic card (GPU) was near 100% while the main processor (CPU) was only around 20% (see the figure below). I understand this is happening because, in this case, the rendering is happening mostly on the GPU, not the CPU.

enter image description here


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