Designing SOCs with Configured Cores

1.5. The Consequences of Performance—in the Macro World

Faster clock rates coupled with more and wider buses do indeed increase processor performance, but at a price. Increasing the clock rate extracts a penalty in terms of power dissipation, as shown in Figure 1.8. In fact, power dissipation rises roughly with the square of the clock-rate increase, so microprocessor power dissipation and energy density have been rising exponentially for three decades. Unfortunately, the result is that the fastest packaged processors today are bumping into the heat-dissipation limits of their packaging and cooling systems. Since their introduction in 1971, cooling design for packaged microprocessors progressed from no special cooling to:

• careful system design ...