Using both GPU on an Mac Pro 2013

[apostolosdt]

TL;DR Summary

Which software can utilise both GPUs on Mac Pro 6,1 (2013)?

I run a MP 6,1 (2013) and it always works with one of its twin video cards. Internet search offers no clues as to what apps can use both. Any advice would be appreciated.

 

[Rive]

I'm not really familiar with the Apple stuff, but as I recall for some older classic PC hardware the second GPU was utilized only for a second display/connector.
Maybe you can find something based on that?

Ps.: apparently, in the Apple World it's not like that?

With two GPUs standard in every Mac Pro configuration, there’s obviously OS support for the configuration. Under Windows, that amounts to basic CrossFire X support.
....

Under OS X the situation is a bit more complicated. There is no system-wide CrossFire X equivalent that will automatically split up rendering tasks across both GPUs. By default, one GPU is setup for display duties while the other is used exclusively for GPU compute workloads. GPUs are notoriously bad at context switching, which can severely limit compute performance if the GPU also has to deal with the rendering workloads associated with display in a modern OS.
...
Due to the nature of the default GPU division under OS X, all games by default will only use a single GPU. It is up to the game developer to recognize and split rendering across both GPUs, which no one is doing at present. Unfortunately firing up two instances of a 3D workload won’t load balance across the two GPUs by default. I ran Unigine Heaven and Valley benchmarks in parallel, unfortunately both were scheduled on the display GPU leaving the compute GPU completely idle.

 

[apostolosdt]

Thanks, Rive, I look into the article.