hi newtusmaximus,
32bit OS without PAE only support ram up to 4 GB.
32-bit Linux with PAE uses a mapping table to allow access to the extra memory (more than 4GB). This is a workaround.
64-bit processors can run 64-bit software, which allows them to use larger amounts of RAM without any workarounds,
allocate more RAM to individual programs (particularly important for games and other demanding applications), and employ more advanced low-level security features.
64-bit processors are backwards-compatible and can run 32-bit software.
This means that you can install a 32-bit operating system on a 64-bit computer.
32-bit applications can run on 64-bit operating systems, but they need the appropriate 32-bit libraries to function.
A “pure” 64-bit edition of Linux wouldn’t be able to run 32-bit applications because it doesn’t have the appropriate libraries.
At this point, the 32-bit compatibility libraries can be quickly installed from the package manager.
They can even be automatically installed when you try to install a package that requires them.
64-bit Linux has a slightly better performance, but uses about 50% more memory then their 32-bit counterparts.
Performance is not noticeably different for most software.
The biggest speedup is probably going to be in math-intensive tasks such as encryption or video encoding and games.
You won't find your browser or music player going noticeably faster.
The gain in speed is tipically 10%.
