64-Bit

From Computing Knowledgebase

64-Bit systems are capable of addressing 1,873,497,444,986,126,336 Bits (234,187,248,265,792 Bytes, or ~213 Terabytes) of System RAM. However, this is just the physical RAM that can be addressed.

The Addressable Virtual Memory size is increased as well with the advent of 64-Bit.