Page 3

Power Supply - Watt Did You Say?

Power consumption then. The 7900 GS requires a decent 12-volt power source for best performance, reliability and most of all that gaming experience of yours. We tested a lot of PSU's lately, be sure to read though a couple of reviews. NVIDIA states that the maximum peak is 82 Watt for the 7900 GS. Since we have a pre-overclocked model that number is slightly higher.

So for a GeForce 7900 GS NVIDIA recommends a 300-350 watt power supply with 22-23 ampere on the 12 volts rails. NVIDIA is recommending nothing too over-the-top in terms of wattage for the power supply unit, yet be aware as that's a lot of Ampage for a 12 volts rails. What we always do with new graphics' cards, we measure the wattage peak with the help of a wattage meter. Slight side note, you are looking at the overall usage of the entire PC.

The meter is placed between the power connector and the PSU. So please understand that using a Wattage meter is not the most reliable way of measuring power consumption. You basically look at how much power is the power circuit from your house pulling from the PSU. So you need to look at the results as being an indication and not an exact science. Let's have a look at power consumption:

Now the table is pretty empty as we moved on towards the more energy efficient Core 2 Duo (Conroe) processor. Okay so we used the X6800, but still.

	Card PC Power Consumption in Watt GeForce 7900 GS 187 GeForce 7900 GT 204 GeForce 7900 GS Galaxy 232 GeForce 7900 GS Inno3D 234 GeForce 7900 GT SLI 275

We simply look at the peak Wattage during a 3DMark05 session to verify power consumption. You are not looking at the power consumption of the graphics card, but of the entire PC. You'll notice that the iChill version card uses roughly 234 Watts.

	An example of how we measure.

So indeed, you need 350 at the least as you want some spare wattage; and 420 Watts or better is definitely recommended. When you buy a new PSU then look at the packaging and check the 12 volts rail on Ampere, it should be 22 AMPS minimal (for the total of +12 volts  rails). If in a later stage or should you immediately decide to go for SLI then we need to redo the math. For two 7900 GS's the 420 Watts PSU should still be sufficient. There are some good SLI certified PSU's out there, again have a look at our PSU reviews.

What would happen if your PSU can't cope with the load?:

• bad 3D performance
• crashing games
• spontaneous resetting PC
• freezes during gameplay
• PSU overload can cause it to break down

So many things can happen.

Dangerous Liaisons - temperatures of the graphics card

That AC cooling is working really well. Let's have a look at the temperatures these coolers produce. We measured at a room temperature of 22 Degrees C.

	Card Temperature in idle (Celsius) Temperature at 100% load in (Celsius) GeForce 7600 GT 42 63 GeForce 7900 GS (Galaxy) 45 61 GeForce 7900 GS (XFX) 42 67 GeForce 7900 GS (Sparkle) 44 66 GeForce 7900 GS (Ref) 44 65 GeForce 7900 GS Inno3D 44 61

A maximum of 61 Degrees C peak temperature was monitored on the card during our test-run. And that's including the default overclock. Nice. The NV silencer really works well. And not only that but it also lives up to it's name. It's silent as well. Let's check that out.