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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 !
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| Card | PC Power Consumption in Watt |
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.
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
For the card the Zalman cooler is 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.
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| Card | Temperature in idle (Celsius) | Temperature at 100% load in (Celsius) |
With the reference cooler you'd see a peak of
of 64 Degrees C, with the Zalman cooler we are way lower to that number at 52 Degrees C yet in a much better and in-audible environment and that's not bad at all. We had the fan rotating at 50% at all times. You can spot the graph above how the heat is building up in the GPU (Zalman cooler results shown). Noise Levels coming from the graphics cardWhen 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.
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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.
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| Card | Sound Level in measured inDBa |
| GeForce 7950 GT (NV Ref & POV) | 44 | ||
| GeForce 7950 GT (Inno3D Zalman) | 39 |
We measure almost 39 dBa on the Inno3D Zalman cooled product, which is to be considered a quiet noise level coming from the entire PC.
