Sorry, Rooster is right, three if your case is large enough to not have the card in your hard drive/disk drive bays.
To find out you will have to guesstimate the distance between the edge of your case to where the graphics card will end:
In this case, measure from one end of the PCI-Express slots out to 10.5 inches, if nothing is in the way for both slots, you are golden.
BTW, your card dimensions are:
10.5x 4.376x 1.5 in