Review 940XM OC plan on linux?

Discussion in 'Alienware M15x' started by crayolacandiis, Apr 20, 2018.

  1. crayolacandiis

    crayolacandiis Newbie

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    Hello, I am not too familiar with overclocking chips without Throttlestop - please let me know if I am doing something that may fry my chip? As an aside, the whole point of using linux is to "bypass" SATA II limitations of the m15x by running 2 x SSDs in software/Grub-recognizable RAID 0 to effectively get SATA III upper limit speeds (~580MB/s).

    msr-tools supposedly allows read/write access to the same place that BIOS/throttlestop writes.
    wrsmr is the associated write tool in sbin

    wrmsr 0x199 -p0 25
    wrmsr 0x199 -p1 25
    wrmsr 0x199 -p2 25
    wrmsr 0x199 -p3 25
    wrmsr 0x1AC 82
    wrmsr 0x1AD 62

    Specifically, is this the correct format for the TDP/TDA imput? Call it cautious, but I'm scared of frying the chip. Thank you!
     
  2. unclewebb

    unclewebb ThrottleStop Author

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    In Windows, run ThrottleStop and monitor those registers to see what values ThrottleStop is writing to them. You can use RW Everything.

    I believe 0x1AD should look like this:

    0x19191919

    0x19 = 25 multiplier so that requests gets you the 25 multiplier whether 1, 2, 3 or 4 cores are active.

    Pretty hard to fry one of these chips. They are very robust. You cannot change the voltage using software so you are pretty safe that way. The Intel public docs explain 0x1AC and 0x1AD but it is a lot easier to just copy what ThrottleStop is doing to those registers.

    Volume 4 - March 2018
    https://software.intel.com/sites/default/files/managed/22/0d/335592-sdm-vol-4.pdf
     
  3. crayolacandiis

    crayolacandiis Newbie

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    How does knowing MSR value for windows help with linux? From my understanding, I thought MSR values are platform specific?

    edit: either way thanks, I'll test when I get my 2nd SSD & update.
     
    Last edited: Apr 21, 2018
  4. crayolacandiis

    crayolacandiis Newbie

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    @unclewebb
    RW Everything doesn't show all the MSR values (lacks 0x199 and thermals)? And I found no differences in the MSR values that it did now.

    I ended up using the win7 SDK debugging rdmsr and got human readable values for 0x199; 9-10 on idle which corresponds to the lowest base clock of the 940XM.

    For the thermals (0x1AC, 0x1AD), the readings seemed hexadecimal but did not correlate to any human readable values. Any ideas here?
     
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