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Not possible to change voltage in Linux? Or what's the lowest voltage 7950 bios?

Discussion in 'AMD / ATI' started by slightboyme, May 7, 2013.

  1. slightboyme New Member

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    hi all,

    I got Sapphire 4L 7950 and I cannot seem to change voltage under Linux. Tried all different tools and all failed.

    Used Trixx under Windows and worked fine(checked with kill-a-watt).

    Does anyone know any way to change voltage under linux?

    I also tried flashing some 1.090V bios and it worked just fine. And I saw some posts saying there is a 0.993V 7950 and does anyone know which bios is that?

    Thanks!
     
  2. OneMoar

    OneMoar

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    the card down clocks when its not underload anyway. with that said that card lacks any software controllable voltage regulators
    please refrain from screwing around with the Vbios its a surefire way to brick the card ... permanently
     
  3. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

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    Did you even read the OP? He says changing volts worked in Windows, but he cannot make it work in linux.
     
  4. slightboyme New Member

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    hey OneMoar, I am not sure what you meant by "lacks any software controllable voltage regulators". I can change the voltage under Windows with Trixx just fine.

    Also regarding voltage, the card has dual bios so it is relatively safe to play with. I just need to find the 7950 bios with the lowest maximum voltage under load. The lowest I can find now is 1.090V but I saw there are some cards that shipped with 0.993V
     
  5. cadaveca

    cadaveca My name is Dave

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    Try Gigabyte Windforce BIOS vF43. 900/1250 MHz clocks, 0.990V load single monitor, 1.09V dual monitor. Memory voltage is 1.5 V. F2 BIOS is same on GPU, but 1.6 V on Memory.


    Screenshot of F2:

    [​IMG]


    Note that I mention that voltage is different depending on number of monitors connected. This is not documented anywhere else. ;) I am not sure if it's just a different power state, or really has something to do with monitors connected, but I can only get that 1.09V on this BIOS with software control, or by connecting second monitor.

    And yes, GPU clocks higher with second monitor attached.
     
    slightboyme says thanks.
  6. OneMoar

    OneMoar

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    he said checked with 'kilo-watt" witch means Absolutely nothing he didn't say anything about actually being-able to adjust the voltage
    everything I have found on that card says that beyond the normal 3 stage adjustment found on the refernce cards there is no voltage control to be had
    its a reference card flashing a windforce bios will most likely brick it .. hard unless msi used the same voltage controller chips as the reference
     
  7. cadaveca

    cadaveca My name is Dave

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    Uh, no. You really should not post about things you are unsure of.:shadedshu


    I have every model of Windforce 7950 card. BIOSes are interchangeable, and originals(not 1000 MHZ cards) used reference PCB, but blue in colour. Bios from 1000 MHz cards works on original cards, too. :p


    my cards:

    http://www.techpowerup.com/forums/showpost.php?p=2885499&postcount=6231

    You can also see all the BIOSes I have played with on these cards in that post, too. ;)
     
    Last edited: May 7, 2013
  8. slightboyme New Member

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    Thanks cadaveca, would you be able to identify which bios I should use under this list?
    http://www.techpowerup.com/vgabios/...te&model=HD 7950&interface=&memType=&memSize=

     
  9. cadaveca

    cadaveca My name is Dave

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    If you look at each listing on it's own by clocking the "details" link, it lists BIOS version there. Look for F43 and F2. Both are there as far as I know.
     
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  10. slightboyme New Member

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    Ah gotcha. Thought F43 and F2 are the model numbers... Great. thanks, will try after work.

    And is it known issue that you cannot change voltage under linux for 7950s?
     
  11. cadaveca

    cadaveca My name is Dave

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    Actually, those BIOSes do come from different models, but the cards are nearly identical in most instances.

    7950:

    F"X"

    F4"X"


    7970:

    F7"X"

    7950 BOOST:

    FX"X"

    FY"X"

    FW"X"

    FZ"X"

    These are all different models, and "X" is the BIOS version number. I hope that's understandable...


    As to Linux, I know nothing about it...:( ...I mean Linux in general, not the issue, of course.
     
  12. slightboyme New Member

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    Ok I flashed the F43 and the F2 bios but I cannot seem to get the voltage to 0.990 for some reason. I can only get 1.090V under load.

    cadaveca, would you be able to upload your bios here? Thanks
     
  13. cadaveca

    cadaveca My name is Dave

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    I am using the F2 BIOS listed in the database. It must be something in this card itself that gives the lowered voltage, as if I read powerplay settings, voltage is supposed to be 1.09V, but as mentioned, that only happens when I have more than one monitor connected. I am also using Windows8.

    Attached anyway though. ;)
     

    Attached Files:

  14. slightboyme New Member

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    Tried this one. Unfortunately it did not work. I guess it must be the card then. Thanks anyways! I will ask around to see if there is a way to undervolt in Linux.
     

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