Is it possible to use my z68's ram on x79 mobo ?

All x79 boards can run in dual channel and maybe triple, I don't remember if they can do triple. Whether or not it will work is another story. If you intend to get an x79 system then you can try the current RAM in it. If it works then great if not then you can buy another set of RAM that is on the motherboard's QVL.