Your problem is the unchecked CPU box -- I have tried to run just CUDA alone unfortunately PG just don't work that way (or I have not found how to do it yet) -- no doubt you have noticed if you only check the CUDA box then update preferences you found it automatically ticked the PPS LLR & SGS LLR boxes
unchecking the CPU box just kills everything
Actually, this is not the case. I have been running CUDA apps this way for quite some time now, and it works just fine. When I want to do some LLR on my CPU, I just enable the CPU box. Otherwise, it is disabled.