ryan@rkavanagh:~$ LD_PRELOAD=/usr/lib/libGL.so /usr/bin/Xgl :0 -fullscreen -accel xv -accel glx:pbuffer -accel xv:pbuffer -ac -kb -audit 0 -br

Fatal server error:
Server is already active for display 0
        If this server is no longer running, remove /tmp/.X0-lock
        and start again.

ryan@rkavanagh:~$              -dpms -dpi 72