other recommended s/w u can use is rivatuner & ati tray tools, but y wanna use other s/w wen it just does the same thing?

depends on wat GC using.
basically GPU can stand up2 100c.

3dmark already 1 of the best tools 2 stress ur gpu. but many people dun know dat actually the built in "custom clock test" on CCC is also actually very effective. run it 10 times, if it doesn't fail, its stable.