Or you can experiment by raising it slowly until you start getting artifacts. Every card is different, so experimentation is the best way to find out where your card tops out. That's what I did anyways.
Hi I also have an overclocking question but for my nVidia FX 5600 XT. The problem is this damn XT. It basically means eXtermenly Time-consuming... or slow. I overclocked it about 10% but dammit I can barely play any games above 10fps. I'm looking into another card but that could be a longgggggggggg while. BTW: I got this as a present, I did not buy it myself .
an XT on Nvidias side don't overclock well and the performance increase is minimal, Depending on your budget and setup I'd sugest going with an Nvidia card if you want to play openGL games (Doom3,Quake3 engine based games) and want Shader Model3 support for future games, and ATI if you want to play everything else without SM3 support
as for oc gfx caard... when I enable overlocking in my gfx card and try the 'find the optimum frequency' it gives me 282 for core and 564 for mem insted of original 250, 500. anyway works fine till now, no overheating etc gonna try to push it a little bit more