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Mysterious Render Test Results, With/Without OpenCL/Metal

Mysterious Render Test Results, With/Without OpenCL/Metal  


New Member
Joined: 12 months ago


(First time in this forum.)

I've recently added a Razer Core X - Thunderbolt 3 eGPU, with a Radeon RX 580 8GB card, to my system. My hope was that it would reduce my (primarily) After Effects/CC2019 rendering times (also sometimes render from Premiere). I have a MacBook Pro (13-inch, 2017, Thunderbolt 3 ports, 2.3 GHz Intel Core i5, 16GB RAM, Mojave 10.14.2.  

However, so far my test render times are mysterious to me. I'm getting about the same results when I select Project Settings > 'Use: Mercury GPU Acceleration (Metal)' and 'Mercury GPU Acceleration (OpenCL)' – (58 mins. for a 10 second segment of fairly complex 4K animation). While selecting 'Use: Mercury Software Only' is significantly *faster* – (50 mins. for the same render). 

The Activity Monitor/GPU History window shows that it is the Radeon card being used during the Metal/OpenCL renders. In the After Effects info. window (Command+i) I have checked beside 'Prefer External GPU'. The Core X is connected directly to the laptop via the supplied USBC cord (not daisy-chained). In fact, everything seems to be in working order, except for the render times. 

I read a benchmark test (somewhere) that showed the Radeon RX 580 8GB as a decent card for this purpose, *for the price*. That test showed it was slower than the more expensive options, or the NVIDIA cards (I'd like to avoid these if possible, to cut down on time lost learning how to make them work with a Mac). But the Radeon RX 580 8GB was only about 20% slower so I decided it was my best option with the budget I have, and maybe I'd upgrade the card in a year or when I can afford to, assuming (correctly I think) that the Core X will be good for a few years.

Any ideas about what I'm missing? Thanks in advance.


Update: BTW, I've been rendering via After Effects (it won't link to Media Encoder, which apparently is a known bug). That said, I see they've just released new versions of both apps, so will re-do the above tests … more soon. 


Rendering via Media Encoder now (bug fixed), same results though, with Metal = 54 minutes...  :-/

Razer Core X - Thunderbolt 3 eGPU
Radeon RX 580 8GB card
MacBook Pro (13-inch, 2017, Thunderbolt 3 ports, 2.3 GHz Intel Core i5, 16GB RAM, Mojave 10.14.2)
Primary software: After Effects/Premiere/CC2019).

Estimable Member
Joined: 1 year ago


I have a gaming box with an rx580 with a mbp 13 2018, although my egpu for some reason is connected only 20gb/s I get on fcpx the same time 3.40 min rendering a 4min 4K Video with Basic adjustments as I get without it although the card is engaged.

A. 2.7 GHz I7 4 Cores, 16Gb, 1TB MBP 13 2018 TB3 , EGPU Gigabyte Gaming Box RX580 8Gb

B. 3.1 GHz I7, 16Gb, 1TB MBP 13 2015 TB2 , EGPU Gigabyte Gaming Box RX580 8Gb