Matching another DDR3 Memory Slot

Hi guys,
I got a Gigabyte GA-790A-UD3 motherboard, with a memory slot from Kingston khX1600C9D3B1/4G, running an AMD processor FX-8350.
I want to expand memory to 8gb, and from the local stores I cannot find another slot like I already have.
Here are screenshots of CPU-Z.


Can you guide me for what memory slot I should be looking for to match the existing one?
Thanks.

Even the same memory series can be on a different memory chips so best is to sell your 4GB and buy 2x4GB kit.
You can also go to the local store with your PC and ask them to check if memory which is on stock is working. Usually it's working but you can never be sure.