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 1.10.1 at 1024×768 resolution. We also ran four game titles at 1920×1080 and averaged the peak results recorded the highest Wattage seen on the meter for the gaming results.
Power Consumption Results: The Zotac GeForce GT 640 had very nice idle power consumption and the entire system used just 98 Watts of power. At full load we hit 200 Watts and that was in both game titles and Furmark! This is around 90 Watts less than the GeForce GTX 660 and GeForce GTX 660 Ti, which is significant. If you don’t need a mainstream or high-end gaming graphic card then something like the GT 640 will save you some money if it is used often.