You have to count power consumed in the whole box, not only the CPU. This reduces the gap between C2D and Atom. OTOH, the Atom is not that much slower than a C2D when you are not doing SSE operations. Their box can be a cluster of servers, not a shared memory monster. 8 boxes with independent SATA, memory and net connections usually perform much better than a single 8-socket box if what you are doing does not involve a shared dataset for all processes.