eGPU on iMAC 27

First, it will do nothing for the iMacs internal display which

will only run off of the internal GPU.

Second, a lot will depend on the software that leverages GPUs

and how it accesses GPUs (if at all). Some will only work with

a system's GPU and others sometimes have options to chose a GPU

to be utilized but none to my knowledge will leverage multiple GPUs.

Third, in terms of improving gaming experiences, it will only be of use

to an external display connected to it.,

Fourth, only the latest Macs with Thunderbolt 3 ports can fully utilize

eGPUs. There are solutions for older Macs but these devices require

some quirky "hacks" for a lack of a better term to function and as

such are vulnerable to any macOS updates,

Before investing in the high price of these devices, I would check to see

how your software will handle it.

When an eGPU is attached, one can switch to/from it via an icon on the menubar. Also, there is GPU history in the Acticity monitor to view internal/eGPU behavior. Apple does not expressly state that the attached eGPU will augment the internal GPU card. The third-party eGPU vendor may clarify this on their site.

In the Mac App Store, the current version of FCPX v10.4.3 does not have any bullet points, or what's new comments about support for an external eGPU. Apple may or may not add this application-specific awareness in a future product release. The current Apple FCPX website also excludes eGPU discussion.

Use an external graphics processor with your Mac.