Ram

Best is to look for RAM on EBay being sold as having come from that system.  It's so old that many newer modules likely won't work, and anything available new will be more expensive than the entire system is worth.

I found the same ram 1333mhz 4gb  but my question is on volt mine is 1.35v and i found with 1.5v . This will problem ?

Yes, it will -- if the system came with  DDR3L (1.35V) memory, do not install 1.5 V DDR3.

So i must find the same brand or i can pick another one brand  , mine laptop has this ram αξιολογήσεις samsung m471b5273dh0-ch9 - 4gb ddr3 1333mhz unbuffered sodimm ... . 

See my original post.  You'd be better off buying RAM that was known to work with this old system.  DDR3 has undergone many revisions over the years -- you may wind up trying multiple modules before one actually works (and the age of the system won't help).

Its a chep purchase and it wil probably work better ... So u tell me to buy exactly the same 4gb i have?

That would be the  best path forward, yes.  That said, the 2G difference won't be substantial.

I can't find the same ram in Greece ..

Unfortunately, that leaves trial and error to see what works.  You may want to see if a local computer shop sells used RAM and will let you try it before buying.

Thank u very much for the help