Is there something like PhenomMsrTweaker for AMD-GPU's?
 

Basically the subject sais it all but ok I will write some more details about my question. :)
I love the tool PhenomMsrTweaker, because it changes the clockrate and corevoltage of my cpu differently in different P-states, just as I like. Is there something like this for GPUs?

Of course I could flash my BIOS for changing different p-state settings but somehow I dont like to do that to my graphics card if it is not fully needed. And then at first I have to find the optimum settings for the idle and full-load moments as well.
This means over- and underclocking as a service would be nice, especially when there is a tool that just plain does that.

Thank you for any serious and helpful hints or advices.

PS: Please don't hate me for not spending hours searching the board. ;)

What are you trying to accomplish? Lower gpu clocks aka "2d desktop"? If so, you may need to edit/flash your bios. If going for just overclocks, msi afterburner always work for me.

I would like to automatically underclock and undervolt my HD 6950 when it idles and overclock it when it is really needed. Since there is at least one mode for semi load I might want to change this as well. I know that I could do this via the BIOS directly but up to now I did not see how I could use Afterburner to change the idle mode. As far as I can see I can change the load-setting to overclock the GPU when it runs with maximum settings. Correct me if I am wrong. :)

Check RBE for card compatibility, It's been a while since I used it. Will need to edit bios and reflash the card, DONT FORGET TO BACKUP CURRENT ONE!

http://www.techpowerup.com/forums/forumdisplay.php?f=63

Does this mean there is no useful software solution for running alternative gpu/ram-clocks and voltage in multiple p-states?
Afterburner e.g. does not let me change the clockspeed any lower than 400Mhz. :( Which is sad.

I'm not sure what you mean. My 5870 automatically idles down to several P states when not in use. It is sitting at 157/300 now, and will kick into 850/1200 at full. There is also a middle setting of 400/something. I don't think the steady volts will age your card any faster, or make it cooler.