here you go
I found this method on another forum a while ago. I don't want to take credit for this great method
There's 3 tools you need:
#1 rthdribl at http://www.daionet.gr.jp/~masa/
#2 3DMARK03 at http://www.futuremark.com
#3 Radclocker at http://www28.brinkster.com/chrisww1942/
Here's the steps to the stress testing:
Use Radclocker to set your Radeon to default (non overclocked) speeds.
Load up rthdribl.
Rthdribl stresses the Radeon's core more than any other program I've scene. It's a 3D tech demo of sorts, but...
It also makes a VERY obvious when there's artifacts. If you seen large white dots flashing around, or if the circling "orbs" start flashing bright light your Radeon's core is set too high !!!
Make sure your memory is at stock speeds through this process. Once you get a core clock speed that doesn't show artifacts in rthdribl then close up rthdribl. You now figured out your stable core stock speed. Write it down.
Set your core clock to default. It's time to overclock your memory.
Load up 3DMark03. Run the "nature" game test in a loop. 3DMark Nature stresses the memory of the Radeon. If you see white spots appearing, then you set your memory too high !!. Lower it until you no longer see white spots/artifacts through the whole game test.
Now you have your memory at the highest stable clock, set. Now bump up the core clock to the speed that was found with rthdribl. You now have what should be your Radeon's stable memory and core overclock settings. Run rthdribl and 3DMark03 Nature with these settings, and fine tune if needed.
Like I said before, this method worked really well for me. I know for sure that I could push my core higher, but I'm a wuss. My memory is set to it's highest stable settings
Hope this helps