GeForce GTX 280 review - 11 - Testing Power consumption | Heat levels | Noise levels

Testing Power consumption

We'll now show you some tests we have done on overall power consumption of the PC. Looking at it from a performance versus wattage point of view, the power consumption is not as bad as I expected it to be. The card according to NVIDIA has a TDP of roughly 237 Watts.

The methodology is simple: We have a device constantly monitoring the power draw from the PC. After we have run all our tests and benchmarks we look at the recorded maximum peak; and that's the bulls-eye you need to observe as the power peak is extremely important. Bare in mind that you are not looking at the power consumption of the graphics card, but the consumption of the entire PC.

Our test system contains a Core 2 Duo X6800 Extreme Processor, the nForce 680i mainboard, a passive water-cooling solution on the CPU, DVD-rom and a WD Raptor drive. The results:

• PC in Idle = 184 Watt
• PC 100% usage (wattage gaming Peak) = 363 Watt

The monitoring device is reporting a maximum system wattage peak at roughly 365 Watts, and for a PC with this high-end card, that is not excessive at all. Idle wattage however should have been lower, yet we believe this was a driver issue. We'll check this in future reviews of board-partner products once a new driver arrives.

* Update - with a retail sample it worked fine. IDLE wattage dropped to roughly 155 Watt, really good.

Recommended Power Supply

So here's my power supply recommendation:

GeForce GTX 260 | 280

• A GeForce GTX 260 requires you to have a 500 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 38 Amps available on the 12 volts rails.
• A GeForce GTX 280 requires you to have a 550 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 40 Amps available on the 12 volts rails.

GeForce GTX 260 | 280 SLI

• A second GeForce GTX 260 requires you to have a 700 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 50 Amps available on the 12 volts rails.
• A second GeForce GTX 280 requires you to have a 800 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 55 Amps available on the 12 volts rails.
• 3-way SLI ...  well check our article on Wednesday please.

There are many good PSU's out there, please do have a look at our many PSU reviews as we have loads of recommended PSU's for you to check out in there. What would happen if your PSU can't cope with the load?:

• bad 3D performance
• crashing games
• spontaneous reset or imminent shutdown of the  PC
• freezes during gameplay
• PSU overload can cause it to break down

Noise Levels coming from the graphics card

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 bought 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. Frequencies below 1kHz and above 6kHz are attenuated, where as frequencies between 1kHz and 6kHz are amplified by the A weighting.

	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 tested all cards on dBA levels. Obviously the reference coolers all perform roughly the same. The customized coolers are either louder or softer depending on what they try to achieve.

• So in IDLE mode, you will not hear the card. We measure less than 38 DBa coming from the PC.
• Gaming with an average title not stressing the GPU too much we can hear the fan a little, we measure roughly 40 DBa.
• When we loop 3DMark Vantage for a while the GPU really heats up, as side-effect the fan RPM will go up even higher, the noise-levels are now 44 DBa which definitely is very hearable, overall these results are okay, really.

The core temperature

Let's have a look at the temperatures this huge cooler offers.

So pretty much we fire off a hefty shader application at the GPU and start monitoring temperature behavior as it would mid-gaming, we literally stress the GPU 100% here. We measured at a set 21 Degrees C room-temperature.

Now a couple of things are interesting here. First of you an see the P-states we discussed earlier. In 2D mode the GPU tries to save power by lowering clocks & voltages, therefore running at a 400 MHz core frequency. The minute we fire off our shader application at the GPU the 3D mode activates and sets the default clocks to what they should be.

In idle you can expect a temperature of 50-55 Degrees C. Pretty normal. Yet once we push the GPU to 100%, the temperatures take a pretty hefty toll and settle at 85 Degrees C, that's 185 degrees F. And that's just really a lot, something I dislike as that's 20 Degrees C away from the 105 C threshold of the GPU jumping into SAFE mode.

Please make sure you PC chassis is very well ventilated.