Power Consumption and Performance per Watt
Testing power consumption has become just as important and relevant in recent years as judging performance of these processors. And unfortunately, testing power consumption has also become a lot more complex than it used to be. Where as we used to just simply test and idle and a load configuration from the wall, new advancements in multiple-core processors, changes in how power planes are controlled on these CPUs and software complications give us a bit more to think about in our power testing.
Idle power consumption is still easy to deal with – here you can see that the new Lynnfield parts are doing a VERY good job of shutting down when they are not needed. They easily use the least power at idle than any other platform available.
For our fully loaded testing, we used Hyper PI and found not the HIGHEST power draw from the processor during the test but rather found the STABLE MAXIMUM power draw during the test – where did the CPU power consumption settle at during the benchmarking process for the longest period. The Core i7-860, with its HyperThreading capability enabled, does use much more power than the Core i5-750 and just marginally less than the i7-870 running at the slightly higher clock speed.
Performance per Watt Measurements
Now I want to evaluate how the different processors tested here relate to each other in terms of performance per watt. To do this I took the load power consumption of each processor and divided it into the benchmark result to create a new metric like Hz/watt (for Euler3D) or FPS/watt for the games.
Though the i7-860 has a good showing here, the additional performance of the higher clock speed offsets the 6 watts lower power draw compared to the Core i7-870 and thus the i7-870 wins the efficiency game here.
The same is seen here.
In Handbrake the results show the advantages of HT technology – the efficiency of the i7-860 outpaces that of the i5-750.
Very similar results again in the Valve Particle Simulation test – the i7-860 makes a strong stance.
Now in gaming, things get interesting. The Core i5-750, Q8400 and Q9650 are the highest rated performance-per-watt winners in World in Conflict. Since the frame rates for all of our tests in gaming were proving to be very similar across the board it obviously makes sense then that the lower power consuming parts are going to come ahead in this metric. The Core i7-860, with basically the same power consumption of the i7-870, can’t really make inroads in this regard.
In our last test, the Core i7-860 barely edges out the i7-870 but can’t compete against the i5-750 in efficiency.
So, after all of this testing, it is clear that while the Core i7-860 is a great part in terms of performance, it doesn’t use less power than the Core i7-870; at least not enough to make a dent in the performance/watt comparisons.