64-bit or 32-bit?  

In most cases, you will go for the 64-bit (x86-64) version because it usually gives better performance. Most computers today are built with the 64-bit architecture, which allows more efficient use of system memory (RAM). Going on 64-bit means the processor reads data in larger chunks each time. It also allows more than 3 GB of data to be addressed. In scientific computing, we typically benefit from added RAM to achieve higher speed. Although using a 64-bit version doubles the memory footprint before exceeding the memory limit, it is often required for large data, such as in scientific computing. Of course, if you have a 32-bit computer, 32-bit is your only choice.