The motherboard supports Dual channel memory. Your memory kit implies it is tripple channel. Basically the optimal performance for the board would be to use 'pairs' of memory. I'm not positive but you should be able to use 2 of the 3 modules for 8GB total but if you can return the memory kit and get a dual channel memory kit it would make more sense.
Thanks for your reply
I'm waiting to try 2 of them working first and then maybe order one more... to do 4 of them
as far as I understand dual channel memory means that I can use 2 of them or 4?! I'm right?
it is still DDR3 240 pin thats all??? right?