Quorum 2 choices for CPU are a wreck. Rakesearch can't keep up with a smaller event like Formula BOINC Sprint. That will end up being a battle of who can grab the most tasks right away before the server catches fire.
The other option is Amicable Numbers. They have a GPU app but from reading their forums it takes quite a few tasks to load up the GPU. Like 7-8+ and they all use a full CPU thread. Its basically CPU bound and the GPU utilization keeps dropping as the # range it checks against grows. I guess if there is no other GPU project happening at the same time the GPUs could be run there too even though its listed as a CPU event.