is 5gb ram is reliable for 32 bit processor
When you have 32bit addressing, you can address 4294967296 bytes - thats 4GB...
But that has nothing whatsoever to do with reliability...
I don't said something about reliability, I just said, that it somehow makes no sense to use 5GB of memory, if you only may use 4 of them...
Concerning the initial question: what did you fear?
That's not necessarily true.
You could, in principle, come up with some sort of Banking scheme to extend the address range...