32-bit Operating System RAM Limit

Note that if you have a 32-bit operating system, you will be limited to using 4 GB of RAM - and in practice something closer to 3.5 GB of RAM since the registry must consume some memory. One of the key advantages of a 64-bit operating system is that the RAM limit is far higher - 16 exabytes, or more than 16 billion GBs.

A computer with a 32-bit processor and 10 GB of RAM, will have 6 GB of RAM that it can't access.

Keep in mind that a 32-bit program can run on a 64-bit system, but the converse is not true. You will not be able to run 64-bit programs on a 32-bit system.