Better memory performance - depending on the architecture, you either end up having a single double-wide (128-bit) chipset-to-memory path (which, in case of the P4 CPU's then matches the CPU-chipset bandwidth) or, in case of nVidia's nForce2 for SocketA, there are two independent memory controllers in a crossbar architecture (crossbar means either controller can access all the RAM in the system. This gives the onboard components room to do DMA transfers through memory, and lets the Athlon XP's prefetch engine have data in the CPU cache before it's even needed by the CPU.
Dual channel also allows for four DDR DIMM slots, which means you can use twice the RAM in your rig, if you're into that sort of thing. Running three sticks of double-sided DDR off one memory controller is always an iffy proposition, with DC, you never have more than two sticks per controller.
Discussion Zen 5 Speculation (EPYC Turin and Strix Point/Granite Ridge - Ryzen 9000)
