@JuezDred:
Compare the same graphics with a 1600Mhz 4gb ram or with 8gb at 1866Mhz… to see if there is a difference or not.
The game will not be influenced by the frequency, if the game asks for more memory then it will perform better with 8GB but you won't notice much difference between having them at 1600 or 1866, even if you put 16Gb you can assign the paging file to the memory and it would be a little faster, but the graphics configuration you have will always have a big influence and what you notice the most is the CPU, a CPU at 4600 will be noticeable faster than one at 3800, I mean in games, it will have better minimums.
Then there is the other case I mentioned if you put four 7970s or four 780s, of course it will appreciate that the computer is very powerful, CPU at 4800 and memory at 2400mhz, but it's because three or four cards will demand the maximum from the CPU and memory, although the higher the resolution the less it demands from the CPU and more from the graphics.
regards