So you HAVE to use --devices and --dualdevices and put the gpus you want on eth on devices and the ones you want to mine etc on dualdevices per the instructions i posted.

Because those instructions state that if you dont specify then cards with 5gb or more will be on eth and cards with 4gb or less will be on etc.

Since yours are all 8gb without specifically assigning them its going to use them all for eth…cause 8gb > 4gb. 

If you add a 4gb card then that 4gb would automatically mine etc with your current command line as long as it has

--dualmode etc --dualstratum

added and in your case would need to have the devices and dualdevices added.