How to Use an External Hard Drive As RAM
Your computer has two types of memory: physical memory and virtual memory. Physical memory refers to the RAM chips installed on your computer, while virtual memory is a reserved section of the hard drive. Windows uses virtual memory to store data for programs that are open but not in use. To boost the amount of virtual memory in your computer, connect an external hard drive to your computer and set Windows to use it as virtual memory.
Click the "Start" menu, right-click "Computer," click "Properties" and click "Advanced system settings" on the left side of the window. Enter the Administrator password if prompted.
Click the "Advanced" tab in the System Properties window, then click the "Settings" button in the "Performance" section of the dialog box.
Click the "Advanced" tab. Click "Change" near the bottom of the window.
Un-check the box next to "Automatically manage paging file size for all drives."
Select your external hard drive from the list. Click "System managed size" to allow your computer to allocate virtual memory on the hard drive. If you want to set a customized virtual memory size, click "Custom," type a minimum and a maximum for the memory size and click "Set." Click "OK" and restart your computer.