5 - Powah, Noise and Heat levels

Power consumption

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 X6800 Extreme Processor, the nForce 680i SLI mainboard, a passive water-cooling solution on the CPU, 2GB memory, DVD-ROM and WD Raptor drive. Have a look:

Observe closely the difference between the 2900, 3850 and new 4870. Quite energy efficient though definitely a high number than the 4850. That's not bad though. Thumbs up to AMD here, that's just brilliant as the performance is nearly the same.

Performance is on par with any modern mid-range graphics card. Our system IDLE power consumption was roughly 175 Watt by the way.

In my view the Radeon HD 4870 series requires you to have a 500 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 32 AMP's on the 12 volts rails for stable power distribution (in a single card configuration). Please make note of the fact that the card uses two 6-pin power connectors.

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, look at 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.

The 4870 does get hot for sure, luckily it has a dual-slot cooler that will exhaust hot air outside the PC. Initially I had hoped that the results would be better with a dual-slot cooler, yet very likely the high clock speeds on this product forfeit that advantage.

Idle temps are roughly 60 Degrees C, yet when the GPU was fully utilized & stressed it reached 88 Degrees C quite fast. That's definitely a lot, I do hope to see some board-partners going for 3rd party cooling, as that number definitely can go down. Though for the GPU itself, this heat level is not an issue. In fact a GPU can reach 120 Degrees C before the fuses blow.

Please make sure you have a very well ventilated 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. 

We start up a benchmark and leave it running for a while. The fan rotational speed remains constant. We take the dBA meter, move away 75 CM and then aim the device at the active fan on the graphics card.

Noise levels are becoming pretty standard these days, again we see the cooler make more noise once it needs to cool down more (RPM spins up) though hearable it's not bad though. Expect roughly 43-44 DBa when the GPU is fully stressed. in idle you hardly can hear the cooler though. So cooling was just fine.