content: Most of the time it is cheaper to buy one card now and then another in a 6 months to a year as the second card will out perform the multi card setup form the original time anyhow. The downside you may have to turn down shadows until you get the new card. Generally it is better off (price wise) buying a new budget card at the end of a cycle, every cycle then buying the top of the line card every third cycle plus two thirds of the time you are like to be running better equal or better performance.  I tend to replace when I start seeing frame rate issue with the games I play, with a new mid range card. Most often this works out around 18 months for me.