Hello - I was running Asteroids through BOINC. I recently added SETI and BOINC has changed drastically. With only Asteroids running each task uses over 90% CPU. When SETI is also running, CPU usage for the tasks drops to 20%, and a "kernel_task" uses hundreds of percentages of CPU. Please advise.

Thank you, in advance.

You didn't say what operating system you're using, but the SETI behavior sounds like a multi-threaded application using more than one core.

I'm running Mac OS 10.11.6. Any suggestions on what I can do?

I'm not very familiar with SETI's applications, but that sounds normal to me. Some projects use a "wrapper" that runs another piece of software that might show up under an unexpected name in a task manager. You might want to ask in the SETI forums, you're more likely to encounter someone who is familiar with the way that particular project works.

SETI hasn't a MT app as far as I know, even the new v8 app isn't multithreaded yet.
At least for the Windows and Linux part I can say that SETI has native BOINC apps and doesn't use a Wrapper. Could be that it is different to Mac but I highly doubt it since they know BOINC very well - SETI and BOINC come from the same university. ;-)
In every case the described behaviour seems quite unusual to me - hundreds of percentage of CPU usgae? Sounds a bit strange and technically isn't possible anyway...