BFG GeForce 9800 GTX H2OC review - 4 - GPU temps, power consumption & noise levels

Power consumption / PSU recommendation

It's time to do some actual testing with these cards. We'll start off by showing 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 really good with the new 55nm products. Our single card test system is a Core 2 Duo E8400 processor (3.0 GHz / 1333 FSB), the nForce 680i SLI mainboard, a passive watercooling solution on the CPU, 2GB memory, DVD-ROM and WD Raptor drive.

We have a new CPU these days and added some new fans & lighting. Our overall Wattage therefore went upwards.

• PC system in idle : 199 watts
• PC system under hefty GPU load : 339 watts

In my view the card series require you to have a 550 Watt power supply unit at minimum if you use it in a high-end system, and I think that's barely on the safe side. Also recommended is 34 AMP's on the 12 volts rails for stable power distribution (on a single card configuration). Notice that the card uses one 6-pin power connector.

There are many good PSU's available, over the years we reviewed a lot of them and have loads of recommended PSU's for you to check out in there, have a look. Things that can 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

The thermal envelope

Let's have a look at the temperatures these cards produce. We measured at a room temperature of 21-22 Degrees C. We then look at the idle temperature and then load the GPU 100% for a couple of minutes and measure the temperature once a second and follow the temperature delta.

• PC system in idle : 40 Degrees C
• PC system under hefty GPU load : ~ 70 Degrees C

Water-cooling or not, the temperatures measures are still pretty extensive considering that water-cooling. It has a lot to do with the massive pre-overclock and related to that, likely higher GPU voltages.

Temperatures can obviously differ per water-cooling setup. Ours actually is fairly high-end. Dual Black Ice 120mm radiator with two fans, we use 3/8" that leads straight to the GPU cooling block. This water-cooling loop does not even cool down the CPU. We have two H2O loops in this system. one for VGA one for the CPU.

What is absolutely great about the water-cooling is that the heat is transferred trough the tubing/coolant towards the radiator. Position it properly and heat is obviously dumped outside the PC.

Noise Levels coming from the graphics card

When graphics cards produce a lot of heat, that heat usually 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. 

Short and simple, the card is water-cooled .. thus does not make any sound. Your water-cooling does have a radiator though, with one or two fans. That's the noise you'll hear.