If this is for gaming, then no, I don't see it doing any good. Very few of today's games even benefit from having more than 8GB of RAM, so only around half your memory is likely getting used as it is. Once games start utilizing enough memory to bring total system usage up around the 16GB mark, it might be worth looking into adding more, but that might not be for another couple years, and RAM prices will probably decrease in the interim.
Plus, as has been said, it's usually best to add sticks of RAM in pairs for better performance.