Power, Heat, And Efficiency
Intel’s Sandy Bridge-E design is a power hog compared to the Sandy Bridge-based Core i7-2600K. On the other hand, Nvidia’s GeForce GTX 580 counteracts the efficiency of Intel's quad-core design from last quarter, sucking down a lot more power than the single GPU driving our new Radeon HD 7970. On average, today's $2600 build uses much less power than its $2400 predecessor.
Remember that total system power consumption is measured at the wall! With that in mind, our new configuration uses about half of the power supply’s rated capacity prior to overclocking. It’s because of this moderate draw that we see the potential for three-way CrossFireX.
Our desire to keep the $2600 PC at its quietest throughout testing compelled us to leave all of its fans in Automatic mode. Temperatures climbed, but noise was somewhat tolerable, even in the face of a full GPU load. All of our fans had at least 20% more capacity, which means that the system’s ability to cope with higher ambient temperatures would likely outlast our self-control. We'd get sick of the increased fan noise and throw this thing out the window long before it overheated.
Efficiency compares energy and work, so we compared average performance to average power consumption in its calculation. The standard-frequency $2400 PC sets the baseline, which is 100% in our performance chart.
Because nothing can be more than 100% efficient, we subtracted the 100% baseline from our calculations before charting our efficiency results. Though power consumption increases with voltage and frequency, similarly increased performance allows our new build to retain its 53% gain, even when it's overclocked.