The 64-bit Decision
The most common reason for a user to install the 64-bit version of Excel, and hence the 64-bit version of PowerPivot, is to gain processing speed and capacity to work with large datasets within a worksheet. Because PowerPivot for Excel uses the in-memory SQL Server Analysis Services (SSAS) engine for data storage, the 32-bit version of Excel may allow users to work with the required data volumes, obviating the need for the 64-bit installation. The examples in this book were all created and tested using 32-bit version of Office. However, there may be reasons for using the 64-bit version of Excel in your specific situation. If that is the case, the 64-bit PowerPivot add-in will accommodate all the examples in this book.
Note The PowerPivot add-in for Excel that you will need is specific to the version of Excel you have installed. Microsoft Office Excel 64-bit must use the 64-bit add-in, and the 32-bit version of Excel must use the 32-bit add-in.