Just two machines? Not much of a render farm. I'd also be wary of operating system differences; the older machine may not work with newer versions of After Effects, and we have NO idea about which version you use.
More cheerful news -- you can't get the two machines to work together for RAM Previews, either.
Yes let's say its a really small farm.!
There are no differences in the operating systems (10.9)
and im using cs6 in both of the machines (but I am planing to upgrade to cc).
so how can I create this "farm" thing ? And if I got you right, it will work only
when exporting a file. not in a ram previews. Right?
Nope, there is no possibility of using two machines to RAM Preview one AE comp. I've never had the luxury of having multiple machines, so I've never even tought about putting together a render farm. Someone wiser than me will have to answer that.