An added feature in Excel XP and up, it is much improved from the add-in of previous versions. Un-checking the 'Save AutoRecover info every:' would switch it off entirely, once checked, you can enter a number of minutes in the spinner control from 1 to 120, (Default is 10). The 'AutoRecover save location:' is the folder that autosaved files should be saved to. Enter the full path in the box.

Excel saves at the set interval a temp file in the folder specified, there is only ever one version in this folder and this is cleared each time the file is successfully saved or Excel is closed normally. If Excel crashes, re-starting will bring up the 'document recovery' task pane allowing you to recover the file at the point it was last auto saved.d.

You also have the ability to switch off document recovery for the active workbook only, which is handy if saves in the active workbook are long-winded, as this will happen each few minutes otherwise.