You're already at the maximum memory limit.
The M2N68-LA motherboard's limitation is 2 x 2 GB of DDR2. How do you propose to add more? How do you propose to change the chipset, BIOS and add more motherboard memory sockets to support more than 4 GB of memory?
These are just some of the physical limitations you can't get around without replacing the entire motherboard with something better.
i dont not that is why i was asking here!
thank you for your help all!