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I try to reduce the stock value of 1.175v with cgminer 3.1.0. I am using Linux. Here is cgminer output:

Select GPU to change settings on:
0
Temp: 78.0 C
Fan Speed: 85% (3191 RPM)
Engine Clock: 1050 MHz
Memory Clock: 1375 Mhz
Vddc: 1.175 V
Activity: 99%
Powertune: 0%
Fan autotune is enabled (0-85)
GPU engine clock autotune is enabled (300-1050)
Change [A]utomatic [E]ngine [F]an [M]emory [V]oltage [P]owertune
Or press any other key to continue
Enter GPU voltage (0.800 - 1.200 V):
1.150
Driver reports success but check values below
Temp: 78.0 C
Fan Speed: 85% (3193 RPM)
Engine Clock: 1050 MHz
Memory Clock: 1375 Mhz
Vddc: 1.175 V
Activity: 99%
Powertune: 0%
Fan autotune is enabled (0-85)
GPU engine clock autotune is enabled (300-1050)
Change [A]utomatic [E]ngine [F]an [M]emory [V]oltage [P]owertune
Or press any other key to continue

It doesn't seem to work.

Suggestions?

Thank you!

not on linux

In Linux the next lower step is combination of 0.95V and Clock of 700MHz

Thank you to both of you.

So if I sum up the answers, On Windows, it is possible, hence this is not a hardware limitation.

I will dig the problem and if I find a way, I'll send you a patch Con.

Greetings,

Which Sapphire do you have mate?

I have the Sapphire vapor-x ghz edition and loads of people try and claim it is voltage locked when it is not.

Unfortunately i know nothing about linux, but in windows you would simply use and older version of MSI Afterburner i.e 2.2.2 or sapphire Trixx.

I have the dual X. It is not exactly the same model than yours. Pretty sure that the hardware do not lock voltage. As CK said, with Linux, you can't change voltage.

I have tried to investigate a little bit more and I found this command line program to tweak the card parameters:

http://code.google.com/p/overdrive5/

The output that I am going to share is

1. The default performance levels
2. The custom performance levels
3. Current settings

What you can deduce is that custom voltage isn't considered.
current activity performance level is screwed. It should be 1.

So in conclusion, the limitation comes from a bug in Catalyst driver. I'm using 13.4

lano1106@whippet2 ~/dev/overdrive5 $ ./overdrive5 -QqA
Overdrive parameters:
   Number of Performance Levels = 2
   Activity Reporting Supported = Yes
   Discrete Performance Levels  = Yes
   Engine Clock =  150.00 - 1500.00 step   5.00 MHz
   Memory Clock =   75.00 - 2000.00 step   5.00 MHz
   Vddc         =   0.800 -   1.200 step   0.005 V
Performance level 0:
   Engine Clock = 300.00 MHz
   Memory Clock = 150.00 MHz
   Vddc         = 0.850 V
Performance level 1:
   Engine Clock = 925.00 MHz
   Memory Clock = 1375.00 MHz
   Vddc         = 1.175 V
Overdrive parameters:
   Number of Performance Levels = 2
   Activity Reporting Supported = Yes
   Discrete Performance Levels  = Yes
   Engine Clock =  150.00 - 1500.00 step   5.00 MHz
   Memory Clock =   75.00 - 2000.00 step   5.00 MHz
   Vddc         =   0.800 -   1.200 step   0.005 V
Performance level 0:
   Engine Clock = 300.00 MHz
   Memory Clock = 150.00 MHz
   Vddc         = 0.850 V
Performance level 1:
   Engine Clock = 975.00 MHz
   Memory Clock = 1375.00 MHz
   Vddc         = 1.150 V
Current Activity:
   Engine Clock       = 975.00 MHz
   Memory Clock       = 1375.00 MHz
   Vddc               = 1.175 V
   Activity           = 99%
   Performance Level  = 3
   Bus Speed          = 8.00 GT/s
   Bus Lanes          = 16/16