Multseat won't work with GeForce GTX 560 and GeForce GT 240

Arch: amd64
CPU: Intel® Core™ i7-3930K
Gentoo Linux: ~and64 (unstable)
X.Org X Server: 1.13.1
nvidia driver: 313.09

Second X instance aways crashes.

log and config files here: https://gist.github.com/4461583

Multiseat configurations are currently not supported.