Yep, that is basically it. If you want the full reasoning, google for DDR2 and 3, but essentially it is this. DDR2 can't go much above say 1066MHz. DDR3 can go 2000 (or more?). However, at equal speeds the extra latencies in DDR3 will slow it down, but at higher speeds (1333+) the extra bandwidth gained makes up for it. You can see that the latencies increase in each step, such as 2 for DDR1, 4 for DDR2, 6 for DDR3, though I have heard they aren't really comparable between ram types, but obviously some latencies are added since DDR3 800 is slower than DDR2 800. This is why you usually don't want to buy a new type of ram in its first generation, as it may actually be slower.