To change the size of the virtual memory paging file
Open Computer Management (Local).
In the console tree, right-click Computer Management (Local), and then select Properties.
On the Advanced tab, click Performance Options, and under Virtual memory, click Change.
In the Drive list, click the drive that contains the paging file you want to change.
Under Paging file size for selected drive, type a new paging file size in megabytes in the Initial Size (MB) or Maximum Size (MB) box, and then click Set.
If you decrease the size of either the minimum or maximum page file settings, you must restart your computer to see the effects of those changes. Increases generally do not require a restart.
Notes
To open Computer Management, click Start, and then click Control Panel. Double-click Administrative Tools, and then double-click Computer Management.
You must be recognized as an administrator or a member of the Administrators group on your computer and on the computer you are managing to perform this task.
You can view or change system properties on a remote computer or a local computer. To access a remote computer, right-click Computer Management (Local), click Connect to another computer, and then select the computer you want to connect to in the list.
For best performance, set the initial size to not less than the recommended size under Total paging file size for all drives. The recommended size is equivalent to 1.5 times the amount of RAM on your system.
Usually, you should leave the paging file at its recommended size, although you might increase its size if you routinely use programs that require a lot of memory.
To delete a paging file, set both initial size and maximum size to zero.
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PS it only uses virtual memory wen its used up all the RAM
it would be beter to increase your RAM as thats faster than virtual memory
