The system idle power requirement is measured at the plug with the operating system running, after two minutes of user inactivity. Using the Core 2 Duo E7200 resulted in 91 W idle power; the E8500 required only 1 W more on the same system. Once again we used several components of the 2008 Tom’s Hardware Reference System.
We measured peak power during all benchmarks and used the highest result. Our only concern: while idle power requirements increase less than 15 percent, peak power increases 40 percent. This is in line with the performance gains—per-Watt performance scales linearly—but processor efficiency decreases with increasing clock speed and operating voltage, as you can see when comparing power consumption and performance levels reached by the Core 2 Duo E8500 with 6 MB L2 cache.