(In reply to comment #7)
> cat /sys/kernel/debug/vgaswitcheroo/switch 
> 0:DIS: :Pwr:0000:01:00.0
> 1:IGD:+:Pwr:0000:00:02.0
> 
> don't seem switched?
> 
> i tried
> echo DIS > /sys/kernel/debug/vgaswitcheroo/switch
> 
> but the screen get completly black...
> 
With "screen" I believe that you're talking about the laptop LVDS?

In that case it seems like the nv card is not wired to that output, thus you'll
need to do the following

* forget about vgaswitcheroo
* Follow the instructions on our wiki [1]


[1] http://nouveau.freedesktop.org/wiki/Optimus/