Issue with (my 1st) eGPU on a Late 2015 iMac
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Issue with (my 1st) eGPU on a Late 2015 iMac  


New Member
Joined: 5 months ago


I've recently built my first eGPU: Sonnet Breakaway Box and AMD Radeon Pro WX 9100.

I ran the (purge-wrangler and set-eGPU) scripts without any hassle, then toggled the "Prefer External GPU" option on the apps as expected. Everything went perfectly, but here's the issue:

When I run apps the discrete GPU still takes the lead, the eGPU barely runs (as seen through Activity Monitor's GPU History.)

Would anyone have a clue why this is happening, and what I can do to solve it? I'm on a Late 2015 Retina 5k iMac, running macOS Mojave 10.14.6.

Any hints or insights on this issue would be much appreciated.

All the best.

To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.


Illustrious Member Admin
Joined: 4 years ago

@reddot, Not all apps have support/optimization for eGPU. The surest way is to use an external monitor (primary) connected to the eGPU.


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2021 15" ASUS TUF Dash F15 [11th,4C,H] + RX 6900 XT @ 32Gbps-M.2 (ADT-Link R43SG) + Win10 2004 // my 1st RX 6900 XT build [build link]