How much does an eGPU enhance the performance the 2017 iMac 5K?
July 7th, 2017, by rob-ART morgan, mad scientist
July, 14th, retested and updated eGPU with RX 580
What gains are to be had by adding an eGPU to the 2017 iMac 5K?
GRAPH LEGEND
eGPUs>1080Ti*2>Built-in - Dual GeForce GTX 1080 Ti (11GB) GPUs one in the Sonnet eFGX Breakaway Box and one in the AKiTiO Node eGFX Box but using only the iMac 5K's built-in display.
eGPUs>1080Ti*2>Dell - Dual GeForce GTX 1080 Ti (11GB) GPUs one in the Sonnet eFGX Breakaway Box and one in the AKiTiO Node eGFX Box with one GPU connected by dual DisplayPort cables to an external Dell 5K display
eGPU>1080Ti>Built-in - One GeForce GTX 1080 Ti (11GB) GPU installed in Sonnet eFGX Breakaway Box but using only the iMac 5K's built-in display
eGPU>1080Ti>Dell - One GeForce GTX 1080 Ti (11GB) GPU installed in Sonnet eFGX Breakaway Box and connected with dual DisplayPort cables to an external Dell 5K display
eGPUs>RX480+580 - One AMD Radeon RX 580 GPU installed in Sonnet eFGX Breakaway Box and one AMD Radeon RX 480 GPU installed in the AKiTiO Node eGFX Box
eGPU>RX580 - One AMD Radeon RX 580 GPU installed in Sonnet eFGX Breakaway Box and connected with dual DisplayPort cables to an external Dell 5K display
Pro580 - '2017' iMac 5K with 4.1GHz Quad-Core i7, 64G of 2400MHz DDR4 memory, Radeon Pro 580 GPU (8GB VRAM), 1TB PCIe based flash storage
NOTE: When using eGPUs with NVIDIA GPUs, we booted with macOS Sierra 10.12.5 and installed the correct NVIDIA web driver. When using eGPUs with AMD 'Ellesmere' (RX 470, 480, 570, 580) GPUs, we booted with macOS High Sierra 10.13 public beta since it supports them without patching the Apple provided AMD drivers.
DaVinci Resolve - Candle 1080p project playback renders Noise Reduction Node (1NR) on-the-fly. GPU Processing mode was set to OpenCL for AMD GPUs and CUDA for the NVIDIA GPU.
(HIGHER frames per second = FASTER)
DaVinci Resolve RED 5K - Playback of RED video is CPU intensive because it is being decoded on the fly.
(HIGHER frames per second = FASTER)
Also, the 'Deliver' function in Resolve is CPU intensive.
(LOWER time in seconds = FASTER)
LuxMark 3 OpenCL - The default option is to render the LuxBall scene using all available GPUs. You can override the default by pausing once the rendering starts. Change settings. Then restart rendering.
(HIGHER KSamples per Second = FASTER)
Blender - Lets you choose one or more GPUs to render a 3D scene using OpenCL or CUDA
(LOWER time in seconds = FASTER)
WHAT DID WE LEARN?
If you are using your iMac 5K to edit video with DaVinci Resolve, you can get a big boost with 1080p playback with Noise Reduction by adding an eGPU with a secondary GPU. However, there is little to be gained with playback or export of RED 4K/5K video since the on-the-fly decoding of RED is CPU intensive.
Did you notice that Resolve did playback and 'deliver' faster when we only used the iMac 5K's built-in display rather than the external Dell 5K display? On the other hand, you will find that with other apps, you must have the eGPU's graphics card directly connected to an external display before the external GPU(s) will be utilized.
LuxMark results reveal the potential of apps that can use multiple GPUs to render OpenCL based projects. Ditto for Blender. And the only way to add a second or third GPU on your iMac 5K or MacBook Pro is with an eGPU box.
The Blender test shows how one NVIDIA GPU rendering with CUDA is twice as fast as three AMD GPUs running OpenCL. And apps like Octane Render won't even function without CUDA capable GPUs.
DUAL eGPUs on 2013 Mac Pro
We booted High Sierra beta on the 2013 Mac Pro. When two eGPUs (one with RX 480, one with RX 580) were plugged in, the OS said, "External GPU Detected - You must log out to begin using the external GPU." So we logged out and logged back in. BOOM! Now we had four AMD GPUs active. The Blender OpenCL render dropped from 678 sec to 304 sec. LuxMark went from 21,781 to 51,706 KSamples/sec. DaVinci Resolve Candle Playback went from 34 to 53 FPS.
Comments? Suggestions? Feel free to email me,
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WHERE TO BUY Thunderbolt 3 GPU expander boxes
You will be able to order the eGFX Breakaway Box direct from Sonnet Technologies or from it's approved resellers. Pricing starts at $299.
The AKiTiO Node eGFX Box can be ordered from B&H Photo Video ($269). Here is a list of other Resellers.
Bizon Tech sells the BizonBOX 2S (works with all Thunderbolt 2 Macs). The BizonBOX 3 (designed for Thunderbolt 3 Macs).
For full comparion of features and implementations of eGPUs, go to egpu.io.
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