If you need to process very high volumes of data, you may need to increase the amount of memory available to the Atom or Molecule. For a 32-bit Atom the default is 512 MB and the highest recommended setting is 1024 MB. A 64-bit Atom can accommodate allocations greater than 1GB.
Also see Atom system requirements, which includes the minimum hardware requirements for processing high volumes of data.
Regarding 32 bit windows systems, the memory is split evenly into to two parts: half for the Kernel and the half for applications(all user programs). For example, if you have installed 4 GB, then all the atoms on your server will only have access to 2 GB.