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It's Guru Power !

Power consumption then. Any videocard obviously requires a stable 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.

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 consumption:

Now the table is pretty empty as we moved on to the more energy efficient Core 2 Duo E6700 processor !

		Card	PC Power Consumption in Watt

GeForce 7900 GS 184GeForce 7900 GT 189GeForce 7950 GT 190 GeForce 7900 GS SLI 245GeForce 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.

So then, 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 minimum (for the total of +12 volts  rails).

If in a later stage or if you immediately decide to go for SLI then we need to redo the math. For two 7950 GT's the 420 Watts PSU could still be sufficient. But I'd like to recommend a 520 Watt SLI-Ready PSU, preferably with dual 12 volts rails.

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.

	An example of how we measure.

Dangerous Liaisons - temperatures of the graphics card

For all cards the coolers are working really well. Let's have a look at the temperatures these design coolers  produce. We measured at a room temperature of 23 Degrees C.

		Card	Temperature in idle (Celsius)	Temperature at 100% load in (Celsius)

Now I already told you that I think the reference coolers are new compared to the 7900 GT for example. It shows, as even the temperatures are a tad better. At idle expect for the reference and POV 7950 GT cards (they all use the same cooler) 45 degrees C (at a 22-23 Degrees C ambient room temperature) and a peak of 64 Degrees C. And that's not bad at all. You can spot the graph above how the heat is buiulding up in the GPU (reference cooler results shown).

The XFX card is a different story, at idle the temperature is way higher due to passive cooling and when utilized it passes a hefty 80 Degrees C which is still within safety margins, but it undeniably is a lot. It will have a very negative effect on overclocking for sure. The upside... the card just doesn't make any friggin noise at all!

When graphics cards produce a lot of heat usually that heat needs to be transported away from the hot core as fast as possible. Often you'll see massive active fan solutions that can indeed get rid of the heat, yet all the fans these days make the PC a noisy son of a gun. I'm doing a little try out today with noise monitoring, so basically the test we do is extremely subjective. We bough a certified dBA meter and will start measuring how many dBA originate from the PC. Why is this subjective you ask? Well, there is always noise in the background, from the streets, from the HD, PSU fan etc etc, so this is by a mile or two not a precise measurement. You could only achieve objective measurement in a sound test chamber.

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement.

		TYPICAL SOUND LEVELS

Jet takeoff (200 feet)

120 dBA

Construction Site

110 dBA

Intolerable

Shout (5 feet)

100 dBA

Heavy truck (50 feet)

90 dBA

Very noisy

Urban street

80 dBA

Automobile interior

70 dBA

Noisy

Normal conversation (3 feet)

60 dBA

Office, classroom

50 dBA

Moderate

Living room

40 dBA

Bedroom at night

30 dBA

Quiet

Broadcast studio

20 dBA

Rustling leaves

10 dBA

Barely audible

We startup a benchmark, we take the dBA meter, move away 75 CM and then aim the device at the active fan on the graphics card.

		Card	Sound Level in measured inDBa
GeForce 7950 GT (NV Ref & POV)	44
GeForce 7950 GT (XFX EXtreme)	--

We measure almost  44 dBa on the  products with reference coolers, which is to be considered a quiet to moderate noise level coming from the entire PC. The XFX card however is passively cooled thus is makes no audible sound at all, bloody fantastic!