есть статья http://welinux.ru/post/3693/ я добавил в xorg.conf
Option "Coolbits" "4"
Section "Screen"
Identifier "Default Screen"
Device "Card0"
DefaultDepth 24
Option "IgnoreDisplayDevices" "TV"
Option "TripleBuffer" "false"
Option "UseEvents" "true"
#BusID "PCI:1:0:0"
Option "Coolbits" "4"
SubSection "Display"
Depth 24
Modes "nvidia-auto-select"
EndSubSection
EndSection