As long as the four sticks of memory match in respects to the speed they run at, the latency timings, and the stated voltage needed to run them then your system should run the four sticks of memory fine to give you a total amount of memory of 14GB.
Arise.
If you have a memory module that is rated at a slower clock speed, or has slightly higher memory latency timings.
Make sure it is placed in the first Dimm memory slot of the motherboard.
Then it will force the other memory sticks to run at the lower speed setting or clock frequency of the lower speed memory module.
As the board always takes the first memory modules settings in most cases for speed latency timings, and voltage settings and apply s them to the rest of the memory in the three other Dimm slots of the motherboard ok.