Page 6 - Wattage, Power Consuming & Temperature

Power Supply Requirements

Now here's where we are going to surprise you a little bit more. Ever since the 7800 was rumored on the web immediately the discussion started on how much power it would consume with that huge transistor count. The 7800 GTX, my friends actually uses less power then the 6800 Ultra. NVIDIA claims it uses 10 watts less then the previous high-end model. And that's lovely! I mean we have quite similar core frequency, basically the same memory, 80 million more transistors and yet it's using less power draw. It likely has something to do with the smaller fabrication process (0.11 micron), which normally results in a lower core voltage for the graphics processor.

So NVIDIA is recommending nothing too dramatic in terms of a power supply unit. At the least a 350 Watt PSU with 22 amps available on the 12 Volts rail should be sufficient.

If you decide to become an uber gamer with two 7800 GTX cards in a SLI setup then you do need to look at something with a little reserve though. 500 Watts with 30 amps on the 12 volts rail. Have a look at this OCZ Modstream 520W PSU we recently reviewed. We actually use it in our test rigs, highly recommended as it can peak to 620 Watts.

Excuse Me, but Watt Did You Say?


With the ongoing trend in an increased power consumption we will check the statement that NVIDIA made about power consumption in. We simply look at the peak Wattage during a 3DMark05 session to verify those claims.

The graphics card consumes 100 Watts at peak during 3D gaming, this is also the reason why we see a 6-pin power connector on the card. Your PCI-Express 16x bus can deliver only 75 Watts to a graphics card. I never understood power requirement decision making as half a year after its release PCI-Express is already running out of juice.

Of course we do what we always do with new graphics' cards, we monitor the overall wattage peak with the help of a wattage meter. Slight side note, you are looking at the overall usage of the PC. The meter is placed between the power connector and the PSU.

In 3DMark the PC shows a maximum peak use of 250-260 Watt. Now you know why 300 Watt Power Supplies are not sufficient anymore these days, 350 at the least.

Temperature wise the cooling design works really efficiently considering this is an uber-high-end-mega-transistor-count graphics cards and combined with that new single slot solution.

At idle, normal operation expect roughly 45 Degrees C. At 100% graphics core utilization we measured a maximum 76 Degrees C peak temperature, which actually is becoming normal. Two years ago I would have freaked out though. Speaking of cooling and thus ventilation, the cooling fan at 100% utilization does not make a lot of noise at all, in fact the HD is producing way more noise then the reference cooler on this NVIDIA graphics card and that's very nice to observe.

The bigger two slow in/exhaust we see on a lot of cards these days actually do have my preference as graphics cards however tend to dump that heat in your PC which on their end can warm up. The dual slot coolers are designed to dump that heat outside the PC. But as always, make sure your PC is well ventilated.