It’s a page file. In good olden days we use to define page file in much simple way. Physical Memory =1.5 time of page file 1 GB RAM = 1.5 GB of Page file. Later game has started changing as new resource intensive application started rolling in and need better handling as well as birth of 64 bit OS and Microsoft made page file rule complex and hence here is the link for Microsoft TechNet article for the same. https://support.microsoft.com/en-us/kb/889654 Note: Remember if your application is disk intensive you should have dedicated disk for Page file.