The Xeon series didn't come out at frequencies that low, so either that box uses 6 busses (that is, 6 "FSBs"

because the P2 only has native support for 2-way SMP. I'm not 100% sure how many busses it would have, nor how much bandwidth it has. It sounds like a specialty box, which might have a different chipset, and perhaps more bandwidth.
But, I thought that the newest clients were more small-cache friendly than older ones. These chips each have 512Kb of L2 cache, so that should help due to main memory bandwidth contention. This is certainly not a box running 12CPUs fighting for main memory bandwidth in the same way that a 2-way SMP does. I'm not sure quite how it works...something to look into.
But Adul's right, in that you'll have to run 12 instances of the client. If you find that the CPUs are fighting for bandwidth too much, a couple could be thrown onto something that requires zilch for bandwidth, two options being RC5 and OGR
