Power Consumption And Temperature
As usual, we measured the power supply's consumption for these cards (which means that the consumption of the entire configuration is measured). We also gauged the power-supply losses, which are approximately 18% in the range we're concerned with.
While it requires an additional six-pin power connector, the 9800 GTX' consumption is actually very close to that of the 8800 GTS 512 MB, which is not surprisingly. The figures were comparable in idle state and just slightly higher under load (running Test Drive Unlimited), as its specifications indicated. Officially, Nvidia specifies 156 W for the 9800 GTX as opposed to "< 150 W" for the 8800 GTS 512 MB, and our results confirmed that.
What that means is that a brand-name 350 W power-supply will be enough to feed a system based on this card. We should mention that despite the reduction in memory quantity and the change in engraving depth, the drop in power consumption compared to the previous generation is nothing to write home about - it works out to only 21 W once you correct for the power-supply losses. On the other hand, the performance/watt yield is obviously much higher (by 52%) compared to the Radeon HD 3870 X2, whose consumption we measured with Unreal Tournament III because it was just too underused with Test Drive Unlimited (We measured 235 W, which was actually less than the 8800 GT).
Despite a limit that's traditionally set at 105°C (the temperature at which the frequencies drop in order to protect the GPU), the rotation speed of the 9800 GTX' fan has clearly been set fairly high in order to stay as far as possible from that temperature. We registered no temperature above 71°C during our tests - only a few degrees more than the temperature at idle. You won't have to worry about this card overheating.