Power, Heat & Noise

Here' we'll take a look at a few of the environmental effects the graphics board has on its surroundings and the rest of the system by looking at the Power usage, Heat and Noise outputs. Due to the measuring equipment we'll not be able to give definitive quantities solely pertaining to the graphics board, as we are unable to entirely isolate it, so each of the metrics are taken at a system level, however where the same system is used and only the graphics board swapped out we can begin to gauge the effects the boards have in relation to one another. In this instance the core temperature is taken directly from the value reported by the driver control panel.

For the testing of all the elements we took the idle noise level results shortly after boot-up, by placing the noise level meter at the bottom of the case, the case side was then placed on and the power and temperature readings were taken. 3DMark03's graphics intensive Game Tests were then looped through 4 times, to load up the graphics, and then on the fifth run of Game Test 2 the power reading was taken, then the core temperature read immediately after dropping out of the 3D scene, and finally the case side removed and the noise level measured. 3DMark03 is used as it has a fairly low CPU utilisation, placing much of the emphasis on the graphics capabilities.

Looking at the system power utilisation we can see that, in fact, despite the larger core size and speed the 7800 GTX does have a slightly lower power utilisation than the PCI Express 6800 Ultra (although we should remember that the 6800 Ultra does have the HSI PCI Express / AGP bridge chip on the package as well), which also carries across to the SLI systems. This is a fairly clear indication that the extra power management features within G70 are working fairly effectively given the performance increase of the 7800 GTX.

Looking at the increase in system power utilisation with the 7800 GTX we see that there is an extra 108W of peak power utilisation, which may give an indication as to what a single board may be drawing.

Both the 7800 GTX and 6800 Ultra have different speeds set for 2D and 3D operation, however there is a much larger core temperature different between the two under idle, 2D loads. This difference may give some indications as to the level of power management features implemented into G70 as with fewer functional elements operational or some running at even lower clocks will increase the core temperatures less. At full loads though, both have fairly similar core temperatures.

Following one from the power draw and core temperature trends the noise generated within the system is also less with the 7800 GTX than the 6800 Ultra, and with a greater variability between idle and load situations allowing it to run much quieter when there isn't too much 3D processing required.