GPU Clock / Memory Clock ratios?

[pbian]

Is there a certain ratio for these 2 values or does it not matter? I have a BFG7900GT and currently it's clocked at 560/(680x2) (stock 475/680x2)cause I can't seem to clock the memory more than that or it will crash? Is that healthy? and is there a way to up that memory clock more?

 

[The_Prophecy]

Is it healthy?.... well, not really. The more you overclock (and the more you consistenly overclock), the shorter the life of the product.