On Mac OS X using eGPU RX 580 not using internal RX 570?
On Mac OS X Hascat recognises and is using allocatable eGPU RX 580 

But Hashcat is ignoring internal RX 570 pro card? It recognises it but skips it?

Also -  is it possible to allocate more of the GPU RAM to Hascat than the 1170 MB that it is using in this case?

The RX580 has 8GB RAM and the RX 570 has 4GB

1. if you use the current github master version, it's a known problem: https://github.com/hashcat/hashcat/issues/2083
2. the VRAM max allocation is a driver restriction (or some would call it "OpenCL spec misinterpretation"), we can't do anything against it. on other operating systems as far as I know, CUDA can allocate more for Nvidia cards than OpenCL. The problem is that the driver only allows to make memory allocations of a maximum size, not more Sad
Thanks Phil

I solved it by applying the patches at #2083 and#2086

So far so good using both the RX 580 and Pro 570