Over the past several years lowering power consumption and increasing performance per watt has become one of the primary goals of Intel’s new processor designs. As you’ll see below, Intel has made great progress since the original performance per watt leader, the Core 2 series CPU.
For measuring power used we plugged our test system in to a Kill-a-Watt power meter. Aside from the motherboard, CPU, and video card the test system used a single SATA DVD drive, an SSD and two 120mm fans. More detail about each platform can be found on the Test Setup page. For idle testing we allowed the system to idle for 15 minutes at the desktop with no programs running and then took our reading. For our CPU load we ran the SMP version of folding@home. This is an intense and consistent load on the CPU and one of the best real world scenarios of 100% CPU usage. It should be noted that power consumption under load was very similar across all of our CPU tests.
The 32nm manufacturing process is certainly paying dividends here; the Intel Core i3/i5/i7 processors are unrivaled at either Idle or Load. As you’ll see in the performance testing, the new Sandy Bridge processors offer astounding performance per watt. The last generation Lynnfield CPUs (Core i5 750 and Core i7 875K) were lauded for their low power use and relatively high performance compared to X58 Nehalem processors. Take special note of the Intel Core i5 661 and Intel Core i5 2500K as they have very similar power profiles, yet extremely different performance characteristics.