<cc_config> <options> <use_all_gpus>1</use_all_gpus> </options> </cc_config>
In some (or most)cases, f.i. WIN XP64/32, you have to Extend your Desktop by using a 2nd monitor or use a Dummy Load.Don't know, how this works in VISTA or WIN 7.
Confirmed. No dummy necessary with latest drivers.