OK, I think that your card belongs to the r7XX generation. If that's right, there should be some power options available to you, but alas, only with relatively new kernels (this would explain why you don't get much battery life at the moment). It appears that Ubuntu 10.04 ships with kernel 2.6.32, whereas the power management code for the radeon driver requires 2.6.35. Your options are: a) look for a more up-to-date kernel version from backports repositories (I don't even know if they are available, but it's possible); b) compile your own kernel (you probably don't want to go through this if you were happy to change distribution); c) install the newest Ubuntu release, currently in beta status, which will be officially out in 30 days; d) install any other distribution shipping a kernel as recent as 2.6.35. Note that the first two options would not suffice, since you'd also need to install recent versions of the driver itself, from backports repositories or compiled from source. Personally, I'd go for option (c) since you are already familiar with Ubuntu.
Originally Posted by Argonisius
Anyway, once you somehow manage to have the required kernel and driver versions, the power state of the card can be consulted through its sysfs interface:
You will have two options at this point, "profile" and "dynpm". The latter is the coolest and most aggressive of the two, aiming to dynamically change the power state of your card depending on the load, but some people noticed artifacts under normal desktop operation. Try it out and see how it feels. The "profile" method enables you to set a power state permanently. Depending on I don't know what, the possible states include:
I use the "low" profile at all times, but I own a different card. Again, try it out.
"default" uses the default clocks and does not change the power state. This is the default behavior.
"auto" selects between "mid" and "high" power states based on the whether the system is on battery power or not. The "low" power state are selected when the monitors are in the dpms off state.
"low" forces the gpu to be in the low power state all the time. Note that "low" can cause display problems on some laptops; this is why auto only uses "low" when displays are off.
"mid" forces the gpu to be in the "mid" power state all the time. The "low" power state is selected when the monitors are in the dpms off state.
"high" forces the gpu to be in the "high" power state all the time. The "low" power state is selected when the monitors are in the dpms off state.
So finally, to set the power method you have to choose between "profile" and "dynpm", like this (as root user):
The "dynpm" method doesn't take any options; while "profile" needs one of the values mentioned above, so to set the lowest power state you'd do:
echo profile > power_method
echo dynpm > power_method
echo low > power_profile
For completeness, you also have the choice of going with the proprietary driver, which has its own set of advantages and some disadvantages. If you do so, there might be a graphical interface to control the power options (I don't really know); if not, your friendly commands are:
The first one should spit the power states available to your card. The second one sets the power state X from the previous list.