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

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#1
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!
 

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#2
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
 

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#3
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
Did you even read the OP? He says changing volts worked in Windows, but he cannot make it work in linux.
 
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#4
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
 

cadaveca

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#5
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!
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:




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.
 

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#6
Did you even read the OP? He says changing volts worked in Windows, but he cannot make it work in linux.
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
 

cadaveca

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#7
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
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. ;)
 
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#8
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=

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:

http://img.techpowerup.org/130507/loaded.jpg


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.
 

cadaveca

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#9
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
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.
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?
 

cadaveca

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#11
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?
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.
 
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#12
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
 

cadaveca

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#13
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
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. ;)
 

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#14
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. ;)
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.