I tested the card both at its regular frequencies and at 615/1100MHz clock rates (these were the maximum stable frequencies of the card at ordinary overclocking, i.e. without modding the cooling system and interfering with the core and memory power circuitry).

The results follow:

So, the NVIDIA GeForce 6600 GT consumes rather small amount of power and, accordingly, its heat dissipation is low, too: 18.5W in the Idle mode and 48W in the Burn mode. This is no wonder since the GeForce 6800 GT is the first graphics processor from NVIDIA to be made with the thinner 0.11-micron tech process, and it is made up of fewer transistors in comparison to the GeForce 6800/GT/Ultra.

Overclocking affects the power consumption of the card but slightly: it grows to about 19W in the Idle mode and to 51W in the Burn mode.

Note that the relatively low power consumption in the Idle mode is achieved without such tricks as frequency reduction or GPU voltage reduction: the GeForce 6600 GT supports independent 2D/3D clock rates, but has identical clock rates in these modes (500/1000MHz) like the top-end GeForce 6800/GT/Ultra chips. The voltage on the graphics processor in 2D and 3D modes is practically the same – 1.431 and 1.477v, according to my measurements.

I will examine the GPU voltage circuit shortly. Right now, here’s a diagram for you that shows the power consumption characteristics of other graphics cards:

So, the GeForce 6600 GT consumes less power than the NVIDIA GeForce FX 5900 Ultra/5950 Ultra, GeForce 6800 Ultra/6800 GT, ATI RADEON X800 XT PE, RADEON 9800 XT, but more power than the NVIDIA GeForce FX 5700 Ultra or the GeForce 6800. You already know the standing of the GeForce 6600 GT among these products, so you can make up an opinion on your own.

Let’s take an in-death view of the power consumption of the GeForce 6600 GT:

The card takes only 0.15W through the 3.3v line of the PCI Express slot and this value doesn’t depend on the clock rates or the load. Thus, almost all the power the card consumes comes from the 12v line. The consumed current on this line is 4.07amp and rises to 4.35amp at overclocking.

So, the GeForce 6600 GT consumes just a little less power from the 12v line than the GeForce 6800 Ultra, and the recommendations about the PSU for the 6800 Ultra – with a good current reserve on the 12v line – seem to be true for the 6600 Ultra, too.