GC overclocking software

How reliable is the maximum 'stable' overclock that Ati Tool automatically finds?? My X800XL is currently 440/540 from its original 400/490. That is the maximum stable overclock according to Ati Tool. But even under load, the temp doesnt pass 65 degrees celsius, and it used to pass 70 at these speeds (before I added some extra cooling). So, basically, do you think it would be safe for me to ignore Ati Tools recommendations and push the card even further, and just burn it in using 3dMark on a loop or something?

ATItool has a slider where you can set the degree of artifact detection. If the slider is all the way to the left, a single artifact detected will cause ATItool to turn the clockspeed down. If the slider is all the way to the right, it'll ignore some of the artifacts.

I guess you could try Find Max Core/Mem with the slider to the right and see how hot your card gets.

I don't have temperature monitoring on my card, so I play it safe and have it lower the clock speed with every artifacts detected.