For testing power consumption, we took our test system and plugged it
into a Kill-A-Watt power meter. For idle numbers, we allowed the system
to idle on the desktop for 15 minutes and took the reading. For load
numbers we measured the peak wattage used by the system while running
the OpenGL benchmark FurMark 1.8.2 at 1280×1024 resolution.
Power Consumption Results: Here we see the GeForce GTX 570 using less power at idle, but more power at load than the GeForce GTX 580. This makes no sense and when we looked into it we found that the GeForce GTX 570 was throttling less than a GeForce GTX 580 video card. This was shown in the Furmark OpenGL benchmark test as the GeForce GTX 570 scored better than a GeForce GTX 580.
Just for fun we ran both the GeForce GTX 580 and GTX 570 with 3DMark Vantage to see how the cards would fare. The GeForce GTX 580 peaked at 358 Watts with a maximum GPU temperature of 73C in game test 1. The GeForce GTX 570, on the other hand, peaked at just 330 Watts with a maximum GPU temperature of 75C in the same test. This 28 Watt difference is more what we expected and the next time that we start over on our benchmarking we will be taking real world power consumptions as our peak using a game rather than a synthetic application.