After upgrading to 13.04, I get this error and other answers (Optirun glxgears: Cannot access secondary GPU - error: [XORG] (EE) No devices detected, 'Cannot access secondary GPU' error with Bumblebee) didn't help.

dpkg -l | grep nvidia



ii  bumblebee-nvidia                              3.2.1-1~raringppa2                          amd64        NVIDIA Optimus support using the proprietary NVIDIA driver

ii  nvidia-310                                    310.44-0ubuntu2                             amd64        NVIDIA binary Xorg driver, kernel module and VDPAU library

ii  nvidia-settings-310                           310.44-0ubuntu1                             amd64        Tool for configuring the NVIDIA graphics driver

This is my /etc/bumblebee/bumblebee.conf:
http://pastebin.com/G9R55VMr

This is /etc/bumblebee/xorg.conf.nvidia: http://pastebin.com/9xNUPp6b

This is /etc/modprobe.d/blacklist.conf: http://pastebin.com/tCnSCz0B

This is /etc/modprobe.d/bumblebee.conf: http://pastebin.com/WtX1LR9d

This is /etc/modprobe.d/nvidia-310_hybrid.conf: http://pastebin.com/CbVg2FN1

My /etc/bumblebee/xorg.conf.d folder contains only 10-dummy.conf file, that is empty.

This is /var/log/Xorg.8.log: http://pastebin.com/iSMXT7aE

This is optirun -vvv glxspheres output: http://pastebin.com/rbyUhRNr

Ask for further details, if needed!