The datasheet will indicate how the chipset controller has been designed. However this does not necessarily mean that your system will feature a port like that. All depends on the your Original Equipment Manufacturer, DELL, and how they implemented the chipset on your system.
In this case, I suggest you to contact your computer manufacturer and check what type of PCI Express* port is available on your system and the revision of PCI Express* revision that it supports. With that information then check with your video card manufacturer and see what cards would they recommend for the type of port in your system and to check for compatibility and installation instructions.