How to manually manage computer memory

When your computer is running low on RAM, and you must have more RAM immediately, Windows uses hard disk space to simulate RAM. This is known as virtual memory. It is also known as the paging file. This is similar to the UNIX swapfile.
By default, the virtual memory paging file (named pagefile.sys) that is created during installation is 1.5 times the RAM on your computer. You can optimize virtual memory use by dividing the space between multiple drives and by removing space from slow or heavily accessed drives. To best optimize your virtual memory space, divide it among as many physical hard drives as possible.
When you select drives, follow these guidelines:
• Try to avoid having a paging file on the same drive as the system files.
• Avoid putting a paging file on a fault-tolerant drive such as a mirrored volume or a RAID-5 volume. Paging files do not require fault-tolerance, and some fault-tolerant computers experience slow data writes because they write data to multiple locations.
• Do not put multiple paging files on different partitions on the same physical disk drive.