If this isn't a joke... really they should be paired (exactly the same type+brand), as different sticks have different timings. Putting 2 unmatched sticks in together is just asking for instant problems.
Dude you will have so many bugs and random crashes its not even worth it . not to mention your ram will be underclocked to the lowest frquency or some ram may not even be being used. go to your system panel in windows and see how much ram is actually being allowed to run .