I am going to get a NVIDIA GeForce RTX 3060 Ti and an eGPU chassis for my computer. I have a MacBook Air (I Know NVIDIA isn't supported for macOS) and use the eGPU on bootcamp.

I have heard that your CPU can bottleneck GPU performance. The main reason why I am purchasing this GPU is to increase Blender Cycles render times. How much bottleneck will my CPU have on this GPU?

Intel Core i5 8210Y (1.6 GHz, Dual-Core, 4 threads)

8 GB LPDDR3 2133 MHz RAM

MacBook Air (Retina, 13-inch, 2019)


With Blender, probably none, because its dune fully on cpu, or fully on gpu. So if you set the render target to CUDA, it will have gpu speeds, no matter of your cpu speed.

  • Yay! What If I set it to OptiX (because RTX GPU?) Should it still be the same?
    – Skyline X
    Oct 21 '21 at 14:42
  • I would stress the "probably" in this answer; OP's CPU is on the very low end side and absolutely could become a bottleneck for such a powerful GPU. The CPU is always being used, it has the responsibility of running the actual Blender software and dispatching rendering commands to the GPU. The eGPU enclosure can also limit bandwidth (but may not be an issue).
    – Romen
    Oct 21 '21 at 21:13
  • @Romen My cpu can overclock to 3.6 GHz which seems pretty fast...
    – Skyline X
    Oct 28 '21 at 1:58
  • Thats turbo, not OC, and yes, 3.6 ghz is not slow
    – Irsu85
    Oct 28 '21 at 6:27
  • 1
    CPU frequency is not an absolute measurement of performance, and the CPU you have is unlikely to run at 3.6 Ghz constantly. Not all i5 CPUs are equal, the ones with the Y on the end are the slowest kind of i5 that Intel makes because they need to aggressively manage their power consumption to avoid getting to hot (usually on laptops/tablets with no fan!). There will definitely be CPU bottlenecking and down-clocking due to thermal management with a Y-series Intel processor.
    – Romen
    Oct 28 '21 at 14:11

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