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    Undervolting using bios. Is it possible?

    Discussion in 'Other Manufacturers' started by black_stormy, Jan 9, 2010.

  1. black_stormy

    black_stormy Newbie

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    Hello everyone!
    Just undervolted my T7300 from 1.2375V to 0.9625V. Right now i m using RMclock utility. What I'm wondering is if there is a way to set those values to be more permanent and so the values wouldn't have to wait for OS and RM to start up to be applied. Can I somehow edit bios? What would the dangers of that be?
     
    black_stormy, Jan 9, 2010
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  2. moral hazard

    moral hazard Notebook Nobel Laureate

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    Probably, though it would be hard to do and you might brick your notebook if you make a bad BIOS mod.

    A safer way would be to modify the dsdt table in your registry, though this is not always possible. If you want to give this a go on your notebook I might be able to provide some help.

    Or another thing you could do is pin mod your PLL to overclock to 2.66ghz and then your CPU would need the 1.2375V.
    I can help you with this.
     
    moral hazard, Jan 9, 2010
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  3. black_stormy

    black_stormy Newbie

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    I' not interested in OCing as I only want my laptop to run cooler and longer on battery. So pin mod isn't an option.

    Bricking my laptop is a possibility as you say and also it would make a cpu upgrade harder as i would need to flash again with original bios, try voltages for new cpu and then make and flash new bios for that cpu.

    But what you mention about registry sounds interesting. I guess in that case making a registry key would be the best solution. I would need to apply it after every reinstall of windows, but i wouldnt have problems with cpu upgrade nor would I need an application to do the undervolting. If it works that is. So yes i would like to try this and any help would be welcome :)
     
    black_stormy, Jan 9, 2010
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  4. moral hazard

    moral hazard Notebook Nobel Laureate

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    First you should follow the attached guide until you have the ASL file.

    Then please upload the file here, I will take a look and check if the code that we want is there
     

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    moral hazard, Jan 9, 2010
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  5. black_stormy

    black_stormy Newbie

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    I don't think it will work. My aml file is empty after step 4.
    HKEY_LOCAL_MACHINE\HARDWARE\ACPI\DSDT\Compal\CRESTLINE\06040000
    there was a 00000000 key in it but after entering it in equus I got an empty aml file.
     

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    • dsdt.zip
      File size:
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    black_stormy, Jan 9, 2010
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  6. moral hazard

    moral hazard Notebook Nobel Laureate

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    We can't work with an empty file :p

    There is another method to extract the dsdt table.

    Let me think for 1 min and I'll give you a link.
     
    moral hazard, Jan 9, 2010
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  7. moral hazard

    moral hazard Notebook Nobel Laureate

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    Ok, follow the following:
    http://forum.notebookreview.com/showpost.php?p=5284894&postcount=48
    http://forum.notebookreview.com/showpost.php?p=5295100&postcount=76
    http://forum.notebookreview.com/showpost.php?p=5295127&postcount=82
    http://forum.notebookreview.com/showpost.php?p=5295129&postcount=83
    http://forum.notebookreview.com/showpost.php?p=5295135&postcount=85
    http://forum.notebookreview.com/showpost.php?p=5295151&postcount=90
    http://forum.notebookreview.com/showpost.php?p=5295156&postcount=91
    http://forum.notebookreview.com/showpost.php?p=5295187&postcount=100

    EDIT: Forget it, one of the most important links is down. I don't have a copy of a program that is needed.
    I can't help, sorry.
     
    moral hazard, Jan 9, 2010
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  8. moral hazard

    moral hazard Notebook Nobel Laureate

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    Actually I think I know why your file is empty, if you enter an incorrect path key then you will have an empty file.

    Make sure you have no typo when you enter this:
    HKEY_LOCAL_MACHINE\HARDWARE\ACPI\DSDT\Compal\CRESTLINE\06040000
     
    moral hazard, Jan 9, 2010
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  9. weinter

    weinter /dev/null

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    Let me clarify:
    Undervolting CPU is done by manipulating the control registers on the CPU.
    It is not hardcoded by any means so it is impossible to hardmod a BIOS undervolt.

    Default values are probably burnt into the CPU itself so it is not editable.
    However undervolting on the GPU is possible to hardcode into the VGA BIOS because the original values are hardcoded via the VGA BIOS itself.

    It is safe to hardcode a VGA undervolt because it implements safe boot voltage meaning the undervolted values will take effect after the driver is initialized.
     
    weinter, Jan 9, 2010
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  10. black_stormy

    black_stormy Newbie

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    You were correct. I wrote CRESTLINE instead of CREASTLNE. :D

    And weinter thanks for the clarification.

    Here is the file:
     

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    black_stormy, Jan 9, 2010
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  11. moral hazard

    moral hazard Notebook Nobel Laureate

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    moral hazard, Jan 9, 2010
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  12. moral hazard

    moral hazard Notebook Nobel Laureate

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    moral hazard, Jan 9, 2010
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  13. weinter

    weinter /dev/null

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    A bit of info here...
    What does the DSDT contain?
    Some function..
    Sleep, Resume Function,Detect Battery,Thermal Behaviour.
    Basically everything as described in the ACPI specs.
     
    weinter, Jan 9, 2010
    #13