I got old 280X cards so using fglrx-updates. I have some 380 and 390X cards tried ubuntu 16.04 with AMGGPU-PRO driver something doing just won’t do OpenCL correctly. So getting about 30 on 390X about 15 on 380s and 16 on the 280Xs I really thing CPU is the way to go in terms of Wattage and initial cost. The GPUs are not massively better. Like 100x. I have my two macs an i7 and a MaCPRO XENON running Sms MacPro at 8 sol/s and i7 at 6 sol/s. I am sure MacPro could do better without the VM