A pagefile is used for caching when memory is low. This pagefile is mostly controlled by windows. It is better to set a value that doesnt change. If you set this pagefile on another disk the race disk doesn't need to spin arround to cache the files.
I use 4 disks in my system and set the pagefile on another disk too, i set it at 2 GB.
Go to My Computer, Properties, Advanced, Performance settings, Advanced, Virtual Memory, Change.
Set a minimum value at 2GB and max value also 2GB, then the pagefile is 2GB and windows doesn't need to find out which size it needs.
Then set the file on another disk, you can do that there aswell.