Serenity Mini, SPCR Edition by Puget Computers

Serenity Mini is the moniker of a Puget computer that is 25% smaller than the Serenity, SPCR Edition v.3. Does the Mini, SPCR Edition, match the ultra-low noise and superb performance of its larger predecessor… even when its i5 Sandy Bridge CPU is overclock-preset to 4.0GHz?

The SPCR Edition v.3 of the Puget Serenity was not only the quietest fan-equipped PC we’ve ever tested
but with an Intel 2600K Sandy Bridge under the hood, also the most capable. After that accomplishment at the beginning of the year, could Puget Computers make any more splashes in 2011? Well, they’re trying, and it would appear they have succeeded.

The latest PC model from Puget to receive SPCR certification is the Serenity Mini. As you can guess from its name, the new model is the Serenity in a smaller package. Jon Bach, the president of Puget Systems, expressed the hope of breaking the 10 [email protected] mark with the Serenity Mini. Keep in mind that SPCR certification does not require a computer to be totally silent; as long as it is quiet and unobtrusive, what matters most is that the company building them maintains acoustic consistency from sample to sample, to assure that all buyers get the same result as the SPCR tested sample. In any case, our anechoic chamber ambient level is 10~11 dBA, and as a result, if a PC achieves less than 10 dBA, we cannot verify it. Mr. Bach’s comment simply underlies his confidence in the silence of his company’s new product.

So how much smaller is the Serenity Mini compared to the Serenity? A Micro-ATX mainboard is used in place of an ATX board. The Mini is housed in an Antec Mini P180 case while the Serenity uses an Antec P183 case. The volume of the cases are 40 liters and 55 liters, so the Mini is about a quarter smaller than the Serenity. The Mini P180 isn’t exactly a small case, however. Its 40 liters is about the same size as many conventional mid-tower ATX cases such as the Antec Solo (I or II) and the Coolermaster Sileo 500. Still, the reduction in overall size may be enough to allow the Mini to be placed atop a desk, especially if the bottom mounted optical drive is going to get much use. In contrast, a P183 case is too tall and deep for convenience on any desktop.

Puget Serenity Mini SPCR Edition atop the table in the anechoic chamber, next to mouse for scale. Animated GIF shows door closed & open.

The table below shows the differences and commonalities between the new Serenity Mini and the Serenity i7, SPCR Edition v.3 . The light blue boxes indicate components common to both.

The range of quieting features added to both models are now described as the Serenity Quiet Modification package. These include the Scythe fans, Scythe Quiet Drive for the hard drive, AcoustiPack case panel treatment, and the fine adjustments to ensure the whole system runs as quietly as possible while still cooled even at high loads.

Here are some notes from Puget about the Serenity Mini:

• The Intel Core i5 2500K CPU in the system is preset to an overclocked speed of 4.0 GHz. This a relatively modest OC, but the combination of overclocking and super low noise is unusual.
• All chassis fans are Scythe Slipstream 800rpm, at 5V.
  We’re very happy with the temperatures, and we are
  confident that we’re not going to find much quieter than this! Temperature
  logs are provided in the packet with the PC.
• The CPU fan is a Scythe Slipstream PWM. Iinstead of relying on the default "Silent"
  QFAN profile, we have custom tuned the fan ramping curve to provide the lowest
  noise levels while maintaining good temperatures. We also tuned it to prevent
  cyclic patterns of the fan ramping up and down. We keep it nice and smooth,
  and in fact, our full load speed is only 30% higher than our idle speed. We
  have this VERY well dialed in.
• For the SPCR edition, we
  "cherry pick" components from our shelf that are the quietest. We’ve
  found that even with the same model of component, there are variations in
  noise level. Hard drive spindle noise, power supply fan noise, motherboard
  electrical noise (we’re so quiet now that that’s one of the loudest items!)…
  we set aside the quietest components for SPCR packages. We’re branding this
  "Picked by ear." (Editor’s note: This is a unique and valuable service given the sample variance among components we often encounter!)
• We’ve done some minor power management tuning in Windows 7. None
  of it is necessary to ensure quiet operation or good temperatures. We wanted
  to make sure customers get the same experience even if they reinstall the
  OS. Mainly, we’re just decreasing the inactivity time before the secondary
  drive spins down.
• A fanless version of the Radeon HD6770
  from Asus is now available, and if it qualifies in this system build with no increase to fan speeds, the new card will be offered as an option.
• The top fan bay is blocked off by a laser-cut black acrylic plate, then acoustipak. It helps reduce sound a little more, and looks a lot nicer.

Mini Serenity
PC page at Puget Custom Computers
The SPCR-certified Silent
PC Program
Serenity i7 PC, v.2

PACKAGING

The system was received in perfect condition, despite the usual rough UPS handling. As with previous Puget samples, the Serenity Mini was impeccably packed in a double carton, as the photos below show.

The Antec Mini P180 carton is packed safely within a larger second carton. A smaller utility carton contains an extensive set of documentation from Puget about the system, as well as all the unused parts and accessories from all the internal components, as well as Windows and rescue disks. When freed from its protective shipping carton, the Mini sported a bright yellow tag warning the user of the need to remove protective Instapak Foam from within. The Instapak is molded around the CPU heatsink/fan and the video card. A little tug, and the foam is easily removed.

INTERNAL TOUR

Once inside, we took a close look to confirm the high quality, meticulous assembly.

The Intel D510 SSD is mounted vertically in the upper drive bay. The secondary drive bay has been removed, replaced altogether by a Scythe 120mm fan mounted on custom acrylic L-brackets; this fan obviously provides fresh airflow to the video card in particular. Note big Gelid Tranquillo CPU cooler and the big passive cooler on the video card. The full-on side view shows the three 120mm fans clearly in a nice more or less straight line of airflow from front to back, the very tidy wiring management, the Seasonic X-560 mounted to draw in air from below the case, the Scythe Quiet Drive which houses the WD Green drive above the bottom-mounted Bluray drive, and the empty space above the CPU area. No top fan is used; the top vent is blocked off by a laser-cut black acrylic plate, then lined with Acoustipak.

Serenity
Mini PC page at Puget Custom Computers
The SPCR-certified Silent
PC Program
Serenity i7 PC, v.2

ACOUSTIC & THERMAL CHARACTERISTICS

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

• Prime
  95 (CPU & memory stress test)
• Speedfan
  (hardware monitoring)
• Throttle
  Watch (monitor CPU throttling due to overheating)
• HWMonitor 1.18
• FurMark
  stability test to stress the integrated GPU.
• Seasonic
  Power Angel AC power meter, used to measure the power consumption
  of the system.
• SPCR anechoic
  chamber and lab
  reference quality sound measurement / recording 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 actual use with real applications.

Typically, the power draw at the start of each test is lower by several watts than that recorded at the end of the test when the stressed components are much hotter. This is typical; as the voltage regulation modules in the motherboard and in the VGA card heats up, they tend to become a bit less efficient.

1. Noise

The Puget Serenity Mini SPCR Edition is just as silent as the Serenity, SPCR Edition v.3. The
measured sound pressure level of <11 [email protected] at idle and not quite 13 dBA at
full system load is at the same level as any fanless PC with no moving parts; the fanless PSU alone will emit enough electronic noise at full load to match this SPL.

At idle, it is really hard to tell that the system is on using only sonic
cues, even sitting next to it on the desktop.
Compared to almost any other fan-equipped PC we’ve encountered
or even assembled ourselves, 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 not unrealistic for a PC that is used atop the desk.

At idle, the spectrum trace for the Serenity Mini was hardly different from the red line that represents the anechoic chamber ambient, which suggests it might have been better than 10 [email protected]. However, at maximum load, it was just a hair louder than the Serenity i7 we last tested. Without these measurements, you’d never know the difference between these systems, however. A 0.4 dBA difference is below most people’s perception threshold. The frequency spectrum of the Serenity i3 Sandy Bridge SPCR Edition shows small rises above the ambient noise floor of the anechoic chamber, mostly below 600Hz. At idle, it is essentially identical to the ambient of the chamber, which is about 10.5 dBA.

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 recommended limits through the
CPU load testing, but they ran significantly hotter when both CPU and GPU
were fully loaded, and the i5 2500K actually ran some 7°C hotter than the i7 2600K in the Serenity v.3. The maximum speed of the CPU fan was 800rpm in the Mini, compared to 880 in the Serenity v.3. This plus the overclock speed to 4.0GHz (from 3.4GHz) probably explains the slightly hotter CPU, but other factors such as a possibly hotter video card and a different case surely come into play.

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
800rpm, as Puget has custom-set the fan controller in the BIOS.

3. Power

The idle state AC power consumption of 63W is very modest, and 5W lower than the Serenity v.3.
The maximum CPU/GPU load
power of 248W AC is up >30W, however. The similar rise in Prime95 load indicates that the increase in power consumption can be attributed to the CPU and motherboard. The obvious explanation for the power increase is the overclocked CPU, but the different motherboard could also have some impact on overall power draw.

4. Performance

No conventional performance benchmarks were run on the system. The performance of the Intel i5-2500k is already well documented in the tech press; it is one of the very best desktop CPUs available today. With the overclocked CPU, the system has the smooth effortless feel of immense power under the hood. The graphics capability
of the ATI HD6750 is also well known. There were no problem
of any kind encountered during our testing. Windows 7 Home Premium 64-bit
provides a mature, smoothly operating environment. The quick boot time of under 35 seconds (from power
button press to actual usability at the desktop) remained unchanged.

CONCLUSIONS

The Serenity Mini SPCR Edition is another worthy addition to Puget’s lineup of super-quiet PC offerings. Like its precessors, this sample is superbly assembled, provides great performance and remains extremely quiet in our test conditions. The system noise would be be rarely audible in normal use. The ambient noise floor in any home or workplace is louder by many decibels.

The Puget’s SPCR Edition PCs remain unique in the use of components cherry picked (or binned, to use a well-known industry
term) for lowest noise. This unique selection service, the carefully chosen fans, the performance and meticulous assembly all combine to make a system that is more than the sum of its parts. The overclocked CPU is an extra bonus that one does not normally associate with a silent PC. Those who want the highest silent video performance to go along with the OC’d CPU can opt for the now available fanless Asus Radeon HD6770 card.

Even with all its performance, the Serenity Mni bears comparison with PCs that have
no moving parts; some of them will actually have more electronic noise (high
pitched, sometimes intermittent whine) than the Serenity Mini. Puget’s SPCR-certified
Serenity Mini is another well-crafted high performance computer at the very limits of silent computing.

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Serenity
Mini PC page at Puget Custom Computers
The SPCR-certified Silent
PC Program
Serenity i7 PC, v.3

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