It seems a little erratic. When I unchecked the same box today in Poser 11, now even when I render multiframe scenes via the Queue manager (i.e. in the background), they are using the CPU (despite selecting the GPU). Worse, when I check the box again, it doesn't fix it. Not sure what is going on there, but I think it's fair to say there are some issues with this setting and it might not always do what it logically should.