i try to explain the problem as detailed as possible even if English isn't my first language:
I have a mix Rig with Nvidia + Amd Cards:
4x GTX 1070
2x HD 7950
1x R9 270x
i tried to run the miner with all cards on opencl launch parameter:

ethminer.exe -F http://******:7777/*******/GTX*** -G --opencl-platform 0

with this command the program only selects the 4 1070s and if i do

ethminer.exe -F http://******:7777/*******/GTX*** -G --opencl-platform 2

i get all my Amd Cards. Is there any command to select all cards to run in opencl ?

JCK

PS: with --opencl-platform 1 i get my Intel Graphic HD.
and with -X i get 0 mh/s.