Sapphire HD 2600 XT 512MB GDDR 3?

I have a sapphire HD 2600 XT 512MB GDDR 3 (the blue one not the red with the flames) and it's running at 796.00 core and 693.00 mem. Is there any use of overclocking it to 843.00 core and 729 mem.? It seems to be stable but I don't know if there is any use for such a small overclock.. Or could I overclock it even more...I've heard the Sapphire cards are already overclocked but I don't know...