Moving Xorg's configuration must not change anything (but you should not have
that file anyway). I believe the "nouveau" driver in Linux-libre 3.5 does not
handle the GTX 500 series:
[ 8.211] (II) NOUVEAU driver Date: Wed Nov 30 18:56:54 2011 +0100
[ 8.211] (II) NOUVEAU driver for NVIDIA chipset families :
[ 8.212] RIVA TNT (NV04)
[ 8.212] RIVA TNT2 (NV05)
[ 8.212] GeForce 256 (NV10)
[ 8.212] GeForce 2 (NV11, NV15)
[ 8.212] GeForce 4MX (NV17, NV18)
[ 8.212] GeForce 3 (NV20)
[ 8.212] GeForce 4Ti (NV25, NV28)
[ 8.212] GeForce FX (NV3x)
[ 8.212] GeForce 6 (NV4x)
[ 8.212] GeForce 7 (G7x)
[ 8.212] GeForce 8 (G8x)
[ 8.212] GeForce GTX 200 (NVA0)
[ 8.212] GeForce GTX 400 (NVC0)
You therefore need to install a more recent kernel.
