Model Eleven by EndPCNoise

SPCR Certified Silent PCs
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EndPCNoise of Vancouver, Washington offers SPCR-designed quiet PC systems in the US

EndPCNoise is the system integrator and vendor of these systems. SPCR has no involvement whatsoever in their sale, distribution or servicing; only the original design and verification of design objectives in the production samples supplied by EndPCNoise. For details of the partnership, please see SPCR Designed Computer Systems.

SPCR Model Eleven: Media Center PC

The Antec Fusion / NSK2400 is a case which I helped to create. I was Antec's primary "functional design" consultant for this case. It was meant specially for HTPC applications with a micro-ATX motherboard, carefully managed airflow, and separate thermal zones for the power supply, hard drives and the CPU/video card. It was styled for easy placement along with other A/V electronics and components. The system I designed around it is one that I would build for myself or for a close friend.

The design goals were:

  • Smooth, powerful performance for all the tasks required of a media PC (including video editing and processing).
  • Good cooling of all the components under a wide range of conditions up to at least 30°C.
  • Gentle acoustic signature.

The requirements for a quiet media PC are somewhat different than those of a quiet desktop computer. When you are working in a quiet room with a computer within a couple of feet away, it needs to produce very little noise for it to be unnoticeable. In measured SPL (sound pressure level), the PC needs to approach 20 dBA@1m. Ideally, it should also be constant in its acoustic level, as changes in noise are more intrusive than steady noise. This is especially true with a computer used for serious work that demands high concentration.

For a quiet media PC, the acoustic requirements vary. If it is in a living room or den, then ideally, the PC should be silent when it's not being used, or at least unobtrusive, so as not to interfere with other activities taking place in the room. But when the system is actually being used for entertainment, then the overall noise level in the room naturally rises, so that the noise of the media PC itself becomes masked. In fact, it can become considerably louder and still not impinge on the music or soundtrack.

My own experience and measurements show that the lowest practical level at which a movie, TV show or music can be listened to is well over 30 dBA@1m. As long as the PC's overall level is at this level or below, and smooth in quality, it will not be audible in actual use. This is not a tough target for a quiet computer, even under load. The only time that increased noise in the PC during use may become objectionable at all is when the mute button is pressed. PC noise can become audible when the sound is muted, and this could be an annoyance for some users.

So acoustically, these were my targets:

  • Silent or extremely quiet when not in use, but quick to start, like a TV or stereo.
  • At least subdued and quiet during actual use.
  • Always smooth.

Tests with the Final Prototype

The final prototype was built by EndPCNoise after about three months of back and forth cooperative developmental work. I've spent about a week with this final prototype, and I am very pleased. The stated objectives have been met, and the system has been as stable as any media PC I've tried.


Most of the internal panel surfaces are covered with AcousticPack.


The business end.

The components in my prototype sample are:

  • ASUS M2NPV-VM motherboard
  • AMD AM2 X2 4200+ processor
  • Corsair XMS2 1GBx2 DDRAM
  • Zalman 7000ALCU CPU heatsink/fan
  • Antec NeoHE 430 ATX power supply
  • Western Digital SE16 500GB hard drive
  • Sony DVD RW DWQ120A optical drive
  • Onboard video (with DVI) was used for this system, but EndPCNoise offers a wide range of fanless video card options.

The key acoustic features (and modifications from the standard Antec case ancillaries) of this system are:

  • Very quiet Antec NeoHE 430 instead of the somewhat noisier stock SU-380 or SU-430 power supply.
  • Single Nexus 120 fan in place of the 2 TriCool 120 fans. The Nexus is quieter and smoother while providing better cooling.
  • Complete deluxe AcoustiPack damping panel treatment of the case.
  • Notebook drive option for those who seek the ultimate in silent computing.
  • Custom "tuning" of each fan speed for optimal acoustic signature

The system came with Windows Media Center installed, with two key settings:

  • Minimal Power Management (with Cool'n'Quiet)
  • Standby mode activated (10 minutes delay)

The fan on the CPU heatsink and the case fan are both undervolted, and the CPU fan is further controlled by the Q-fan feature on the Asus motherboard. Q-fan caused the CPU fan to speed up subtly after a few minutes at the full load test. This is reflected in the SPL measurements in the table below. Ambient conditions were ~17 dBA and 21°C.

Activity
CPU
HDD
SPL
dBA@1m
AC Power
standby
-
-
n/a (silent)
0W
idle
32°C
40°C
23
68W
Full load
(CPUBurn x2)
66°C
42°C
25
138W

All the temperatures are well within a safe range. In normal usage, the system is powered on 24/7. When the controls have not been accessed for more than 10 minutes, it goes into standby mode, with everything in the system powering down. It is then absolutely silent. If you have MCE set up to record a TV program, the system powers itself up at the specified time, records the program, then if there is no activity, goes back into standby. In other words, in normal usage, if the system is not actually being operated, it is utterly silent.

When the system is being used, the single biggest source of apparent noise is the WD hard drive, which causes a slight low frequency hum when the system is placed on resonant surfaces such as a hollow table top. This noise is very low in level, however, and dissipates quickly with a bit of distance. When you are seated 6~8 feet away, as in a typical TV room, the noise is extremely subtle, and not possible to hear with any music, TV program or movie sound track on.

A bit of seek noise is also audible from close up (within 3 feet) when the hard drive is writing or reading. Again, when the system is in use, this noise is below the level of entertainment sounds from the speakers.

Note that EndPCNoise offers a notebook drive option that will eliminate even this trace level of low frequency hum or seek noise from the hard drive. If the notebook option is chosen, because of its relatively low capacity. I would strongly recommend a large external storage drive with a 2-meter remote connection to store movies, shows and music. The 2m distance should allow you to position the external storage in a closet, damped drawer or other acoustically isolated space to keep its noise contribution to a minimum.

For best results, a few inches of breathing space should be allowed all around the unit. Jamming it into a tight cavity or shelf, especially in a closed cabinet, is not recommended. You risk overheating and higher noise due to fans ramping up in speed. This advice applies to all computers and most A/V electronics.

Summary

The SPCR Model Eleven prototype built by EndPCNoise works exactly as intended. It is a silent servant when not being actively used, and capable, stable and quiet when used for its primary role at the heart of a digital entertainment center.

EndPCNoise order page for SPCR Model Eleven Media Center PC



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