2. Noise Levels For Various Usage Scenarios

We measured the noise levels of these systems for a number of different usage scenarios. First we started each system up and then measured noise levels at a distance of about 20 inches (50 cm) in front of the machine where your head might be in a normal sitting position. This value indicates idle mode noise levels, or what you might expect to hear during normal office work.

Our next test consisted of playing back a video from DVD and measuring noise levels. To simulate a processing load typical when encoding or decoding audio or video files we used the Burnmax tool to impose a heavy load on each notebook's CPU. After that, we combined loading of both the CPU and graphics processor on each machine. The resulting noise levels are a good indicator of what you're likely to experience when playing 3D games.

Our analysis of these measurements follows our measurement diagrams.

Analysis Of Noise Testing Results

Though the notebooks from Acer, Asus, and HP in idle mode are nearly inaudible, the Alienware unit cranks out noise levels at 46.5 dB(A) even when idle. For daily office use, this notebook is decidedly too loud. You can get a little relief by throttling the graphics processor clock rate back in the driver to its minimal value, but that turns the noise down only to 44.2 dB(A). And of course, you won't want to play any games with this setting in effect.

In the DVD scenario, the fast spinning optical drives on the Aspire 5672 WLMi and the Asus A7J are responsible for the bulk of the noise we measured from those units. This is particularly objectionable on a unit like the A7J, which is supposed to be a convergence device suitable for entertainment center use. But who wants to put a noisy DVD player in their living or family room? On the Aurora M7700 the biggest culprit is the CPU fan, compared to which the HP nx9240 is balm for one's ears.

Under heavy CPU loads, the fans in all these units run at their maximum rotational speeds after about one minute. In this scenario the Acer Aspire 5672 WLMi is relatively quiet, whereas none will want to linger too long in the vicinity of the Aurora M7700. But once the CPU load is removed, the fans in the Acer, Asus and Alienware units spin down after about 30 seconds to run at their minimal rotation speeds (as in idle mode). The HP Compaq nx9420 spins down in just a few seconds for a marked sonic contrast.

When both the CPU and graphics processor are heavily loaded, the fans on all units spin up to maximum speed after just a few seconds. After ceasing this strenuous exercise, it takes up to two minutes before the fan speeds and noise outputs drop back to idle mode levels.

Subjectively, we found the sound profile of the HP Compaq nx9240 the most tolerable (or perhaps, least objectionable) of this bunch.