So I kinda like to keep some balance so i'll explain my configs as they stand first:

I have 2 gpus and a 4 core cpu

I dedicate GPU 0 to einstein
I dedicate GPU 1 (fastest) to SETI@home

My CPU Based projects have set to max concurrent as 1

I wish to actively work on all projects as much as possible versus letting boinc decide one day to work on those and another day to work on the other ones at its own decision

Right now I have run into an issue and its not using all the cores yet work units are available to the other projects.

GPU 0 running einstein with 1 cpu core
GPU 1 runnign seti@home

ATLAS is using one cpu core
LHC us running one cpu core for each of the 2 subproject tasks its running

that totals four cpu cores at the moment but sometimes I go a day without using one of my cpu cores and yet projects liek enigma have work units available.

Noticed it does say cpu not highest priority is there anyway to have to get work for spare cores when it comes down to it and not just leave cores unused?

At the moment <max_concurrent> isn't considered in work fetch. Work fetch thinks you have enough tasks in cache but doesn't realise not all of them can't be run yet. Tweaking cache size to smaller or larger or lowering <rec_half_life_days> might help.