It's true that whenever you use more RAM and more sticks overclocks tend to go down as does stability. However as far as ram bandwidth goes at a constant MHZ, you want to use as many slots as possible. This again is assuming we are only concerned with speaking of ram throughput. It's simple logic 4 slots is better then 2 even with the same about of ram. It's simply a matter of the memory controller's assignments. This is usually what causes the system instability, along with the greater need for power consumption. (4 sticks of 512 need more power then 2 sticks of 1024) The controller has more physical objects to address.