Case Basics & Recommendations

Cases|Damping | Reference|Recommended
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  • Update Feb 13, 2012 - Minor text changes, additions and deletions to recommended cases.
  • Update Feb 11, 2011 - Added notes on Gaming Cases, PSU positioning; minor text changes.
  • Update Dec 13, 2010 - Silverstone GU07 and Lian Li PC-08 added
  • April 7, 2010 - Complete Overhaul & Update to article and recommendations.
  • Update Nov 16, 2007 - Many additions and deletions to recommendations.
  • Update Oct 17, 2007 - Antec P182 added.
  • Update Aug 17, 2006 - Many additions to recommendations, plus new section on Acoustics around the media PC.
  • Update Jan 3, 2006 - Antec P150 recommendation put on hold until bundled NeoHE PSU issues are fully resolved.
  • Update Nov 9, 2005 - Additions, deletions and changes all around.
  • Update May 7, 2005 - A few changes to the lists.
  • Update Jan 23, 2005 - Text revised, new Antec, Coolermaster and SilverStone cases added.
  • Update Aug 3, 2004 - YY Mars and SilverStone SST-LC01 cases added.
  • Update May 31, 2004 - A huge number of changes and additions.
  • First published March 12, 2003

INTRODUCTION

Some people argue that a PC begins with the case. Others say it's merely the outer skin in which a PC is enclosed. Whichever your point of view, it's clear that cases don't make noise by themselves, it's the components inside that do. Still, there's no doubt that a case has a very significant role to play in silent computing.


What's in a case? Components that produce heat and noise.

Since this reference article was first posted in early 2003, PC case design has evolved tremendously, substantially more than in the previous decade. I wrote in earlier editions,

"Much of the discussion here refers to a tower-style ATX case. There are many other case styles, including very small towers, tall towers, horizontal desktops, both large and small, silm desktops, and the "lunch box" size / shape popularized by Shuttle and Mini-ITX case builders, and even smaller Ultra SFF cases. Fundamental points about cooling and airflow apply to all case types. Just keep in mind that the low-front-to-high-back airflow path considered ideal for ATX towers will not apply the same way for horizontally laid out cases. "

The mid tower ATX case is still dominant, but the generic ATX mid-tower design pictured in the drawing above no longer has much relevance for today's Silent PC. More on that later.

THE ROLE OF A CASE

The conventional perspective says that a case performs these functions:

  • Adheres to various form factors in order to hold and house the various components that make up a PC: PSU, motherboard, PCI cards, drives, fans, etc.
  • Provides EMI and noise shielding.
  • Allows for airflow through the case for cooling of the components within.
  • Offers conectivity through conveniently placed ports
  • Looks nice.

The silent PC perspective is different, mainly in emphasis. Form factor adherence for proper interfacing with standard computer components is assumed (and mandatory) for all cases; EMI shielding, cosmetics and connectivity are secondary to the key properties of:

  1. Extremely unrestricted airflow vents,
  2. Indirect paths for noise escaping the case,
  3. Well-directed airflow paths within the case,
  4. Low resonance, sturdy construction and low sound transmission.
  5. Quiet, good quality fans (although easy enough to replace with quieter ones)

Antec P183 — the latest version of the case that established new standards in anti-noise features and independent thermal zones for improved cooling.

 

1. Unrestricted Airflow Vents

There are several reasons why unrestricted aiflow vents are so important for silent computing:

  • A main anti-noise strategy is the use of quiet fans at reduced speed to eliminate fan noise. Because airflow volume and pressure is considerably lower than in a standard PC, any obstruction at the vents has a potentially large negative effect in temperatures.
  • Case fans are normally mounted at the airflow vents. Anyone who has paid attention to the behavior of fans knows that a physical obstruction (impedance, in the fan jargon) close to the fan blades causes turbulence noise. The greater the impedance, the greater the noise and the lower the airflow.

The ideal vent is one with no grill at all, but in the face of realities such as curious toddlers or pets, something like a wire grill or minimalist honeycomb-pattern grill is about the best compromise. In the front, it is normal for a plastic or metal bezel to be used for a cosmetically pleasing apparance. The front intake air vent can be seriously hampered by the design of the front panel and bezel. Many case makers do not pay enough attention to the front panel vent design.


The Tiny Morex T1610 fanless case works only with Intel Atom mini-ITX Intel D945GSEJT board. The only source of noise is a very quiet notebook drive; an SSD would make it completely silent.

2. Indirect Escape Paths for Noise

The above points might suggest that the best silent case is one with a completely open hole in the front for an intake fan. But that's not quite true, because this allows the noise of the fan to go directly out of the case, to the users' ears. The requirement of indirect noise escape paths means that the front bezel should act as a baffle that forces sound to travel around angles so that it loses intensity before exiting the case, while at the same time, allowing the air to flow unrestricted. A similar arrangement for back panel vents would also be useful, but no known case has this feature. The noise from the back panel, which usually points away from the user, is also less critical than the noise from the front.

3. Well-directed Airflow Path in the Case

This is best achieved by minimizing the number of extraneous holes in the case. Randomly placed holes on the sides, for example, tend to disrupt directed flow of air. This means you have airflow, which almost always causes some noise, but it doesn't effect any cooling: That's a waste.

4. High Resistance to Vibration, Sturdy Construction and Good Sound Insulation

The requirement of high resistance to vibration and good sound insulation calls for heavier, thicker panels joined solidly. This includes the way removable panels are affixed to the case Noise caused by panels vibrating in sympathy with fans and hard drives is much more insidious and prevalent than most people would believe. This phenomenon adds a haze of background hum, mostly in the lower frequencies but not limited to them. In general, this requirement tends to exclude aluminum cases, which usually resonate and vibrate more readily than steel cases. (More about vibration and aluminum cases on the next page. )

A Few Words about Cosmetics: Our preference is for clean, lean minimalist lines dictated by function. But... if a case "looks ugly" and works quietly and efficiently, we tend to see it as beautiful: Form follows function. Matters of taste are really personal. Choose one that does not annoy you every time you look at it. Cases meant for use as Home Theater PC generally need to look nicer because most Audio / Video gear looks nicer, and you may want the PC to match cosmetically with other AV gear. But again, a HPTC case that looks nice without providing essential performance is not a good case, in our view.

GAMING CASES

A class of gaming-optimized cases represent an approch that is almost diametrically opposed to some of the above points:

  • Instead of baffled intake vents, they use a completely perforated front facia for maximum intake airflow.
  • Rather than a well-direct airflow path in the case, they place vents and fans (often huge fans that approach 20cm diameter) on top and on the sides.

Some years before, there would have been no way for such cases to be used for silent computers; the unsupressed noise from the components would have been too much. Today, heatsinks and fans for the hottest components, the CPU and the GPU, have progressed to the point where the additional airflow in these wide-open gaming cases can be used to keep all the fans running at minimal speed, with the end result beling a surprisingly low level of noise. Good Resistance to Vibration, and Sturdy Construction are still high on the checklist for such cases though.



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