Power Consumption

To complete our today’s discussion we have also tested the power consumption of the systems (without the monitor) built on CPUs from two different generations: Penryn and Nehalem. For this test we chose the top processors from Extreme Edition series working at the same frequency of 3.2GHz: Core 2 Extreme QX9770 and Core i7-965 Extreme Edition. All power-saving technologies including Enhanced Intel SpeedStep and Turbo Boost Technology were enabled. We used Prime95 utility to load our CPUs to their maximum:

Power consumption of platforms based on CPUs from different generations is close not only in the official specifications, but also in real tests. The delta is no more than 4% for two CPUs working at the same clock frequencies. Core i7 consumes less power in idle mode due to more aggressive power-efficient modes and its ability to disconnect cores from the power supply line. Core 2 Extreme turned out slightly more economical under workload.

However, do not forget that Core i7 works faster when the load is multi-threaded even though its heat dissipation is similar to that of its predecessor. It means that the new CPU on Nehalem microarchitecture can boast better performance-per-watt.

To prove this statement we measured the electric energy of both systems during their work on the same tasks in PCMark Vantage benchmark emulating real work of different sorts. This value illustrates very well how much power these systems need to solve identical tasks. And again Core i7-965 Extreme Edition based platform showed its best having spent only 140W *h, while a system with Core 2 Extreme QX9770 inside required 159W*h of electricity.