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Thread: Fan not throtling on thinkpad e520 when discrete (radeon) graphics is off

  1. #1
    Join Date
    Dec 2006
    Location
    Slovenia, Europe
    Beans
    21
    Distro
    Ubuntu 7.10 Gutsy Gibbon

    Question Fan not throtling on thinkpad e520 when discrete (radeon) graphics is off

    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

  2. #2
    Join Date
    Dec 2006
    Location
    Slovenia, Europe
    Beans
    21
    Distro
    Ubuntu 7.10 Gutsy Gibbon

    Re: Fan not throtling on thinkpad e520 when discrete (radeon) graphics is off

    *bump*

    I have also found a thread on Lenovo Community Forums about this problem:

    http://forums.lenovo.com/t5/ThinkPad...ue/td-p/586829

    I'm still trying to figure it out weather the problem lies in drivers or bios or the hardware implementation itself.

    Regards!

  3. #3
    Join Date
    Jan 2012
    Beans
    1

    Re: Fan not throtling on thinkpad e520 when discrete (radeon) graphics is off

    Quote Originally Posted by bss View Post
    *bump*

    I have also found a thread on Lenovo Community Forums about this problem:

    http://forums.lenovo.com/t5/ThinkPad...ue/td-p/586829

    I'm still trying to figure it out weather the problem lies in drivers or bios or the hardware implementation itself.

    Regards!
    The Lenovo Forum thread talks about the same issue on Windows systems. I have a Thinkpad Edge E520 1143-3NG using Debian Wheezy (with kernel 3.2.0) and have the same problem with the latest BIOS 1.22 too. I think this indicates a hardware/BIOS problem. Maybe turning the discrete graphics off also turns of the thermal sensor triggering the fan.

    I turn on the discrete GPU using vga_switcheroo when I do some CPU intensive work until there is some better workaround available.

  4. #4
    Join Date
    Nov 2011
    Beans
    1

    Re: Fan not throtling on thinkpad e520 when discrete (radeon) graphics is off

    Any news on this? Problem still present at my e420 witch ati+intel graphics...fans start working only after i switch the radeon card back on

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