The SR-2 Classified has two CPUs and two banks of memory, one for each CPU. The right CPU and RAM bank (furthest from the back ports) is the primary CPU and RAM bank. The left CPU and RAM bank (closest to the back ports) is the secondary CPU and RAM bank. You can run the motherboard with just one CPU and set of RAM as long as they are in on the same side of the board.
You can disable one or the other side by adjusting the jumpers at the middle top of the motherobard. Default all CPUs are enabled with the jumpers in the left position. CPU0 Jumper is on top while CPU1 Jumper is below. To disable a CPU, move the jumper over to the right position.