While the maximum RAM limit for 32-bit Windows 7 editions is 4GB, when it comes to 64-bit editions, the amount of memory that the OS can address depends on which edition you are running. It’s around 64GB or 128GB depending on the manufacturer or the chipset itself. If you're serious about your PC, then I consider this to be the new default. 8GB RAM. To reach the required 16.8 million terabytes in 384GB tiles would take 44.8 million tiles. The maximum RAM is determined by the operating ststem, if you are using a 32 bit operating system it will support a maximim of 4 GB (2^32 -1). If you’re talking about the highest RAM that you can get in a normal desktop PC. A RAM-tile then holds 384GB of RAM. RAM controls the speed and memory in your computer. Now we're into performance territory. If you are using a 64 bit opearting system it will support ( 2^64–1), it will come about 2 TB of RAM. The original IBM PC, introduced around 1982, used a CPU with 20 address lines, giving a maximum memory limit of 1MB, but the design specification reserved the top 384KB for firmware, leaving 640K for normal RAM. Different types of RAM are available for different machines. How to Find Out the Maximum RAM Capacity for Your Computer. Random Access Memory (RAM) is an important component of your computer just like the hard drive.