[GUIDE] How to underclock mem in Ubuntu

[Okama]

Hi all,

I'm not sure if this has been posted before or not. I searched but didn't find something clear enough, so I decide to create one 

There are 2 ways (as I know) to modify the GPU clock/mem under Linux.
1. Use a tool to override AMD driver
2. Modify the VGA bios

I will go with the no.1 first.

1. sudo apt-get install git libwxgtk2.8-dev
2. git clone git://amdovdrvctrl.git.sourceforge.net/gitroot/amdovdrvctrl/amdovdrvctrl 
3. cd amdovdrvctrl
4. wget http://download2-developer.amd.com/amd/GPU/zip/ADL_SDK_3.0.zip
5. unzip ADL_SDK_3.0.zip -d ADL_SDK
6. make
7. sudo make install
8. AMDOverdriveCtrl << start the program

You can chage the memory clock in Overdrive tab
http://1.bp.blogspot.com/-mdAOf7aWo34/TV0kMlaVd2I/AAAAAAAABCU/jDmJOnllA-s/s320/ati_4.png
(The image above is from here)

By the way, using AMDOverdriveCtrl is a little inconvenient in case you have more than 2 cards. And I decide to re-flash the VGA bios with new clock settings.

I use Radeon BIOS editor, GPU-Z & ATI WinFlash Note: This is Windows tools  .

1. Save the current BIOS with GPU-Z (You can see the Save button in the same line with BIOS Version)
http://tpucdn.com/gpuz/screen1.gif
2. In RBE, open your saved file
3. Change the clock settings
http://tpucdn.com/rbe/RBE_Clocks_small.png
4. Save the custom BIOS, flash with ATI Winflash and there you go.

Tips: Tried to find the stable settings for my VGA first (core/mem) and then set them to default clock in BIOS. Don't need to do anything more in Linux 

Using the above methods, my 5870 gives me ~430Mhash/s with 1000/300 mem/core (voltage remains) and save some few Watts  .
http://img41.imageshack.us/img41/7438/screenshot20110603at352.png
 

Refs: 
Tutorial on how to use RBE (Radeon BIOS Editor)

Feel free to give away something if you like my post 1AAf3a8RT8anVvomhMNovZqcZvzMpu4SAA

[1715633441]

1715633441

[Prze_koles]

I can't use AMDOverdriveCtrl, says Segmentation Fault

[CubedRoot]

What about adjusting voltages on ATI cards in Linux?

[mikegogulski]

$ aticonfig --adapter=all --od-enable
$ aticonfig --adapter=all --odsc=###,%%% (where ###=core clock and %%%=memory clock)