Shaan5 :
Ok, I think I'll just bite the bullet and buy another 8GB Stick
Make sure it's IDENTICAL.
Also, the performance difference depends significantly on what CPU, GPU you have as well as what games you are playing. The faster the CPU the more likely the bottleneck would be.
It's also been tested to much confusion though the results I finally trusted show up to 15% difference at times even while gaming.
One of the major testing difficulties is that people have compared average performance instead of LOW performance (due to sudden CPU bottleneck) which is more critical. Unfortunately outside of benchmarks there tends to be a margin of error when testing LOWEST cpu usage which makes duplicating tests difficult.
*More than 8GB isn't currently much benefit (aside from video editing, Virtual Machines etc) however in the FUTURE with DX12 games Microsoft has discussed scenarios where a significant amount of System Memory might be used; they did a demo which showed several GB's of texture data for Mars in System Memory which kept being swapped into Video memory while zooming in to the planet (Shared Tile's).