Maybe a strange question, but why would you add more ram?
You already have 16GB installed and that 16GB will hardly ever be all in use.
For example here is overview of Memory Usage from 1 of my systems. It has 2 x 4Gb Dominator Platinum 2133 CL9 installed. I use one off the Microsoft Tools from the SysInternals package called Process Explorer, this gives in depth details about a lot of system functions. The memory tab off the System Information Tool contains the interesting stuff:
- The version of Windows in use determines part off the amount off memory in that Windows uses: a lot of (older) windows 32bit versions do not support > 4GB. The 64bit versions do.
- A real weird rule of thumb from Microsoft is that it looks at the physical installed amount off memory. In my case: 8.324.415 k (=8 GB). Microsoft than multiplies the amount by 2: 16.646.988 k (=16GB). So the memory is actually seen as 16GB, the extra 8GB is the windows page file.
- Tasks are prioritized by windows (W7 64bit Ultimate in my case): tasks with lower priority get scheduled for period of low system usage.
- The actual usage = PEAK LIMIT reached 79,58% on my system that had been up for: 15 hours, meanwhile I played some games, did a lot of Photoshop work (=actually one of the Tools that benefits from large amounts of memory).
- The current limit is like 33%.
- The amount off available memory is 5.355.532 K (approx 5,1 GB), so plenty off head room!
So the system doesn't use all available resources by far. In my situation adding more dram does not render any improvement and is pretty much useless. This applies to most peeps with "normal" systems and normal use.
Additionally on a Z77, Z87 or Z97 rigg using more than 2 dram sticks puts more strain on the IMC. This actually lowers the overclocking capacity of the CPU. My advice: No need to buy extra dram. If want some extra perfomance: try to raise the dram frequency on your rigg, the 4790K has an excellent IMC that easily sustains higher dram speed.
Memory usage in my work/game rigg: