Hello guys!

I have a strange issue. I have just bought a new Lenovo thinkpad edge e520 and installed ubuntu on it. It has switchable (hybrid) graphics so I am able to turn off the Discrete (Radeon) graphics in order to save power. But when I do (i did it on boot in /etc/rc.local: echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch) the fan speed does not resspond to any load. That is the laptop gets really hot (cpu temp about 75-80 C), when discrete graphics is turned off at boot.

However, if I turn the discrete graphics card on, the fan starts working (throtles nicely and cools down the laptop.). If I turn the discrete graphics off again then the fan stays at the same speed as it was when the graphics card was turned off.

Sensors output:
Code:
acpitz-virtual-0
Adapter: Virtual device
temp1:        +20.0°C  (crit = +120.0°C)

radeon-pci-0100
Adapter: PCI adapter
temp1:       -128.0°C  

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +78.0°C  (high = +86.0°C, crit = +100.0°C)
Core 0:         +79.0°C  (high = +86.0°C, crit = +100.0°C)
Core 1:         +78.0°C  (high = +86.0°C, crit = +100.0°C)

thinkpad-isa-0000
Adapter: ISA adapter
fan1:           0 RPM
I have also noticed that
Code:
acpitz-virtual-0
Adapter: Virtual device
temp1:        +20.0°C  (crit = +120.0°C)
is not changing if the discrete graphics is off.

If I run windows, then the fan works OK.

I'm running Ubuntu 11.10 amd64 - Linux 3.0.0-14-generic