It's not the RAM per say, it's the added traces, or number of tracks, the CPU has to use the access that memory. When then are in two sticks, no sweat. Double that to 4, that means twice the total distance your data may have to travel between the CPU and RAM sticks. Now imagine you have your page file, Chrom with 20 tabs open, then decide to start a game. Well, you have enough RAM for none of that data to be pushed off to the side, but the CPU might have to process data on three separate sticks if RAM, so it only stands to reason that this us going to take more time. Sometimes you can work around this by increasing RAM voltage, but many times you would need to settle for the slightly lower speed. BUT, if you are maxing out 16 GB of RAM, the RAM upgrade upgrade should far surpass the frequency drop as far as performance goes.