Lenovo ThinkCentre M58p Eco USFF: Green Corporate SFF PC

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ACOUSTIC ANALYSIS

Much of the listening was done in a quiet 20' x 10' room with 8' ceiling where ambient conditions were 20 dBA and 23°C. Acoustic testing was done mostly in the anechoic chamber, where the ambient level was 10~11 dBA and the temperature was 23°C. Idle measurements were taken 5~15 minutes after boot or reboot, whenever none of the temperatures had changed for several minutes. Load measurements were taken after >20 minutes of Prime95.

Here are the measurements from the anechoic chamber on our sample.

Acoustics: Lenovo M58p Eco USFF
Test State
SPL (dBA)
System Power
1m
0.6m
Idle
21
27
41W
Maximum
27
32
97W

Lenovo's specified ISO 7779 user position SPL (at a distance of about 0.6 meters) is 24 dBA, which would be audibly quieter than the 27 dBA we measured. Another 0.4 meter distance reduced the SPL to just 21 dBA, but a small PC like the M58p Eco USFF will be put on the desk next to the monitor, which is usually much closer, about where ISO 7779 specifies.

The sound is not loud but it has complex tonalities which can be annoying. The spikes at 450Hz, 1.8kHz and 3.5kHz in the spectrum response below, taken from 0.6m about 45° left of the front, indicate some of these tonalities. The much lower level spikes at around 10kHz may also be audible.

Some of these tonal peaks were caused by the hard drive which made the top panel vibrate. Pressing firmly on the top panel damped the vibrations and elminated much of the higher frequency tones, making the overall sound less intrusive. So the mechanically decoupled mounting of the hard drive is not quite effective enough to stop its vibrations from affecting the overall acoustics. A 15-lb stack of magazines and books atop the the Lenovo had an acoustic effect similar to my hand. The $69 optional Vertical PC and Monitor Stand II shown on the first page of this article might reduce the perceived noise, with the monitor blocking the PC. The stand looks like it clamps the chassis, which could also have positive vibration damping effects.

At full load, the fan sped up to a fairly high speed, and the system became too loud to be considered quiet, at least not at 0.6m distance. But even at 1m distance, it was a plainly audible, intrusive 27 dBA. Note the peaks at 250Hz, 4~500Hz, 1kHz, and 1.8kHz.

 

VS. OTHER REVIEWED SMALL SYSTEMS

The overall sonic signature of the Lenovo was not dissimilar to the Dell Studio Hybrid: A complex tonal sound rather than the preferred smooth broadband "whoosh" which is so much less intrusive.

The Asus Eee Box B202 is a low power net box not capable of 1080p HD video reproduction, and smaller than the Lenovo. However, newer models B204 / B206 incorporate a 256MB ATI Radeon HD 3400 GPU for HD video capability in the same chassis and should have similar acoustics.

The Anitec SPCR-certified SilenT3 was also added to the comparison mix. This is a system with capabilities similar to the Dell, including HD video playback. In size, it's a touch bigger than the Lenovo.

Mini System Acoustics: SPL at ISO 7779 User Position (0.6m)
-
Idle
Load
Lenovo M58p Eco USFF
27 dBA
32 dBA
26 dBA
35 dBA
21 dBA
21 dBA
24 dBA
26dBA

The M58p Eco USFF does not fare well in the comparison, falling in last place with the Dell.

MP3 SOUND RECORDING

These recordings were made with a high resolution, lab quality, digital recording system inside SPCR's own 11 dBA ambient anechoic chamber, then converted to LAME 128kbps encoded MP3s. We've listened long and hard to ensure there is no audible degradation from the original WAV files to these MP3s. They represent a quick snapshot of what we heard during the review. Most of the recordings listed below were made with the mic at 1m distance.

Note that the Lenovo was recorded at 0.6m as well. This is the ISO 7779 user position distance, and it is more realistic than the 1m distance for small PCs which are almost always placed close to the monitor. For now, the Lenovo is the only product we have recordings for at 0.6m. We'll be adding 0.6m recordings to all small PCs in future.

For the most realistic results, set the volume so that the starting ambient level is just barely audible, then don't change the volume setting again while comparing all the sound files.

Comparable System sound files:

  • Asus Eee Box B202 at idle, 18 dBA@1m and 14 dBA@1m (behind LCD monitor) -- The recording of the Eee Box was made with the unit at idle, and the microphone 1m away, first on a table in the hemi-anechoic chamber, and then mounted on the back of an LCD monitor, and the microphone 1m away from the front of the monitor. It starts with the room ambient, followed by the product's noise. The acoustics of the Eee Box barely changes with load, which is why only idle noise was recorded; there's virtually no audible difference at full load.


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