Add boinc to the video group.
ls -l /dev/nvidia*
crw-rw---- 1 root video 195, 0 2009-09-11 23:07 /dev/nvidia0
crw-rw---- 1 root video 195, 255 2009-09-11 23:07 /dev/nvidiactl
sudo vi /etc/group
etc...
I guess since your's is working, I'm posting this for others who might run into this.