Niagara2’s SOC design is optimized for performance/watt
and enables reduction of total power consumption and power
density at the chip and system level. Niagara2’s simplified
pipeline and reduced speculation in instruction execution reduces
wasted power. A Niagara2-based system is a lot more
power efficient as compared to, for example, a system with eight
single-core processors (on separate chips) each having their
own I/O (DRAM, networking, and PCI-Express) interfaces.
Such a system will have 8 times the I/O interfaces and hence
will consume a lot more power in those interfaces. Also, extra
power will be consumed in driving the off-chip multi-processor
coherency fabric. In comparison, for Niagara2 there are only
one set of I/O interfaces and the coherency between the eight
processor cores is handled on chip by the crossbar, which
consumes less than 1 W of power.