Agree with Rhossydd, adding in ram often causes stability issues or slower speed overall versus leaving in the original set. Sell on your current set and add in 2x 8gb matched pair. That will have a huge boost. First, check your motherboard specs to see what's supported, although official support doesn't actually mean others don't work. It's just the voodoo of PC building, so many variations and iterations that listing everything is often a nightmare.
Unfortunately, ram can be a bugger to get right.