Puget Serenity, SPCR Edition v.2

SPCR Certified Silent PCs | Complete|Mobile Systems
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ACOUSTIC & THERMAL CHARACTERISTICS

This is the core of the SPCR certification for a PC. Many tools were used to analyze the system:

The basic approach is to assess the noise, thermal and power characteristics at idle, and then at full CPU and GPU loads. The testing was conducted entirely in the SPCR anechoic chamber, with the door open to ensure adequate room ventilation when noise measurements or recordings were not being performed. Measurements under load were recorded 60 minutes after the tests were started. This is an artificially long time for both CPU and GPU to be at full 100% load; it would hardly ever happen in acutal use with real applications.

Test Results: New Puget Serenity SPCR Edition PC (v.2)
Criteria
idle
1080p play
Prime95
Prime95+
Furmark
AC power
70W
82~87W
191~196W
257~262W
CPU
30°C
35~38°C
68°C
74°C
GPU
40°C
42~48°C
46°C
84°C
Mainboard
38°C
38~41°C
55°C
63°C
HDD
32°C
32°C
32°C
33°C
SPL - dBA@1m
11
11
12
12.8
SPL - ISO 7779 Seated User Position (0.6m)
12
12
14
15
Ambient conditions: 21°C, 10 dBA - Off/Sleep Mode: 3.5W
Max safe temps - CPU: 80°C, GPU: 100°C, HDD: 55°C

Previous Test Results: Puget Serenity SPCR Edition PC (original)
Criteria
idle
1080p play
Prime95
Prime95+
Furmark
AC power
70W
80~86W
173~180W
232~240W
CPU
28°C
35~37°C
55°C
55°C
GPU
33°C
40~42°C
44°C
68°C
Mainboard
30°C
35~37°C
35°C
55°C
HDD
26°C
26°C
26°C
27°C
SPL - dBA@1m
14
18
18
18
SPL - ISO 7779 Seated User Position (0.6m)
16
20
20
20
Ambient conditions: 20°C, 10 dBA - Sleep Mode Power: 3.4W
Max safe temps - CPU: 80°C, GPU: 100°C, HDD: 55°C

1. Noise

The new Puget Serenity SPCR Edition is silent at idle. The measured sound pressure level of 11 dBA@1m at idle and not quite 13 dBA at full system load puts it at the same level as any fanless PC with a single, super-well muffled hard drive. Compared to the original sample tested three months ago, this system is obviously quieter, at idle and especially at full load; subjectively, the 5 dB difference is perceived as about a 50% increase (or 33% decrease). To put it another way, the new system is quieter at full load than the original system was at idle. That's pretty impressive, especially as the original was extremely quiet.

At idle, it's really hard to tell that the system is on using only sonic cues, even sitting next to it (with the system on the floor as it should be). The subjective impression (compared to the original) is of significantly reduced hum at idle, and much quieter overall at full load, when the overall noise is still barely audible. Compared to any other fan-equipped PC we've encountered or even assembled ourself, this one is quieter.

The ISO 7779 computer noise standard's defined "Seated User Position" SPL places the microphone about 0.6m away from the top/front of the PC, which explains the 2 dBA higher readings. This is an unrealistically close distance for a PC in a case as large as the Antec P183, which is designed for placement on the floor; few users would put it on top of the desk.



The frequency spectrum of the new Serenity SPCR Edition shows a small rise between 100Hz and 250Hz, but the level of the peak arely reaches -10 dBA. The HDD noise is also improved somehow as the expected 90Hz fundamental of the WD Green Power drive is simply mising. The cherry picking of the quietest components for the SPCR Edition probably explains this. The rest of the spectrum is almost identical to the ambient of the anechoic chamber when it has no noise sources within. The SPL represented by the red line is about 10.5 dBA.


The original Serenity showed a bit of a tonal peak at ~90Hz, at the fundamental frequency of the WD Green hard drive, and another around 200Hz. The first peak is missing in the new version and the second is much reduced. It seems pretty clear that cherry picking the components led to a significant reduction in overall noise.

Audio Recordings of this system were not made. There is no point. It is virtually silent in the anechoic chamber and it will be silent in almost any environment.

2. Cooling

The various components stayed well under maximum safe limits through the CPU load testing, but they ran significantly hotter when both CPU and GPU were fully loaded. The maximum speed of the CPU fan dropped from 1030rpm in the previous version to 880rpm in the current configuration. They are different fans, and do not necessarily have the same airflow at the same speed, but it's clear the new fan at 880rpm does not move as much air as the previous one at 1030rpm. In any case, despite higher overall temperatures, the components temperatures remained safely below maximum limits.

Puget expressly states that this PC is designed for quiet operation in an ambient of up to 30°C. This is a fair statement under normal use conditions. Under such conditions, the CPU fan will probably still not rise much beyond 880rpm, as it Puget has custom-set the fan controller in the BIOS.

3. Power

The idle state AC power consumption of 70W is fairly modest for a system with the computing power of an Intel i7-875 CPU and the graphics capability of the ATI HD5750, a mid-level gaming card. While the maximum CPU/GPU load power of 260W will not win any green prizes, it is apropos for a system with these components. The 20W increase from the original system at the same max load is somewhat expected due to the higher clock speed of the CPU and the increase in RAM. The AntecCP-1000's efficiency is shy of the best, but it's quite good, some 85% at the 260W AC power draw level. More moderate use, such as playing a 1080p HD video, barely raised the power level 15W over the idle. Finally, the power difference at load can also reflect sample variance in the components of the two systems. (Rarely are two components identical.)

4. Performance

No conventional performance benchmarks were run on the system. The high performance characteristics of the Intel i7, the ATI HD5750 video card and the Intel SSD are all very well documented in dozens of tech web sites. There were no problem of any kind encountered during our testing. Windows 7 Home Premium 64-bit provides a mature, smoothly operating environment, with full access to the 8 GB of installed RAM. The quick boot time of under 35 seconds (from power button press to actual usability at the desktop) made possible by the Intel SSD was nice to see, as well as the effective and quick sleep mode, where the minuscule 3.4W power draw makes powering the system off/on almost completely unnecessary.

CONCLUSIONS

The new Puget Serenity SPCR Edition is totally unique in at least one aspect: The use of components cherry picked (or binned, to use an well-known industry term) for lowest noise. This unique selection service, the replacement Scythe Slipstream fans, and the tweaks and refinements for improved noise combine to make our second Serenity sample the quietest fan-equipped PC we've ever tested — or even built for ourselves. It bears comparison even with PCs that have no moving parts; some of them will actully have more electronic noise (high pitched, sometimes intermittent whine) than the Serenity. Our hats are off to the Puget development team for their pursuit of excellence. Puget's SPCR-certified Serenity PC is a truly well-crafted high performance computer at the cutting edge of silent computing.

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Serenity PC page at Puget Custom Computers
The SPCR-certified Silent PC Program
Original Puget Serenity SPCR Edition Review

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Comment on this article in the SPCR Forums.



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