I have 12 cores and a GPU. I'm trying to do 2 MT tasks w 5 cores each + a GPU task. So my settings are 5 threads and 3 max tasks. This works fine most of the time, but sometimes I'll return to it and it's doing 1 CPU, 1 GPU, and holding one GPU WU. (That's weird too because it's set to not pre-fetch.)

My hypothesis is that sometimes when it reports a CPU WU, it sees there's room for another task and prioritizes fetching a GPU task. Is that the case, and can I control it?

Don't set for a fixed number of tasks. Set for 5 cores/task, and in the boinc client, set it to use 10/12 (83.3->84%) CPU. This should accomplish what you're looking for.
____________
My lucky #: 60133106^131072+1 (GFN 17-mega)

I have 12 cores and a GPU. I'm trying to do 2 MT tasks w 5 cores each + a GPU task. So my settings are 5 threads and 3 max tasks. This works fine most of the time, but sometimes I'll return to it and it's doing 1 CPU, 1 GPU, and holding one GPU WU. (That's weird too because it's set to not pre-fetch.)

My hypothesis is that sometimes when it reports a CPU WU, it sees there's room for another task and prioritizes fetching a GPU task. Is that the case, and can I control it?

Thanks all!