Best option available on modern Motherboards? 2x2GB (4GB) or 2x4GB (8GB) with lowest latency for that Motherboard. For example, let's say you had two DDR3-1600 modules of 1GB each installed in dual-channel mode, you would get great throughput (bandwidth/transfer speed), but might suffer from a lack of total available RAM. This is mode (two modules) provides the best throughput performance for the machine, although not necessarily the best performance altogether. This means that you can install two DDR/DDR2/DDR3 RAM modules (or 'sticks) that are identical in the opposite colored slots and achieve dual channel (or 128-bit) mode.
Dual channel generally requires two RAM modules or more, and usually channels are color coded on the Motherboard.
What this means is that - in modern CPUs, a memory path is 64-bits wide. Dual channel works just the way you would think it would - it provides dual channels (access paths) to RAM.
