Case Basics & Recommendations

Cases|Damping | Reference|Recommended
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  • Update Oct 23, 2014 - Minor adjustments.
  • Update Sept 28, 2014 - Complete rewrite of main article & umpteen changes to recommended lists
  • 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 young readers looking at the drawing below will hardly recognize it: An early standard case design for an ATX motherboard, with projected airflow. The ATX motherboard specification was created by Intel in 1995 in an effort to standardize form factors for better interchangeability of parts. (Check Form Factors.) Astonishing, in the fast-paced world of computing, that ATX remains today, more than two decades later. While the spec hasn't changed, cases for ATX motherboards have undergone tremendous changes in the past decade, such that most current retail cases are dramatically different from the case in the drawing.


Early ATX case & theoretical airflow

Since this reference article was first written 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 ATX mid-tower design pictured in the above drawing has been relegated to the cheapest, most generic models. The drawing below shows a typical current case design and airflow. Note how the power supply position has been turned upside down in comparison to earlier ATX cases. This makes for a huge thermal and acoustic difference.


Straight through airflow in Antec P18x series.


Top and bottom panel vents on Fractal Design ARC XL increase airflow cooling for the system. Top vents can be used for large water cooler radiator.

 

THE ROLE OF A CASE

The conventional perspective says that a case performs these functions:

  • Adheres to various form factors in order to 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 is assumed (and mandatory) for all cases; EMI shielding, looks 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 they are easy enough to replace if necessary)

Unusual Silverstone RV05 rotates the motherboard a quarter turn so that airflow goes from bottom to top, for help from natural convection.

 

1. Unrestricted Airflow Vents

There are several reasons why unrestricted airflow 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 minimal wire grill is about the best compromise. In the front of the case, 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. Many case makers do not pay enough attention to the front panel vent design.

2. Indirect Escape Paths for Noise

The above points suggests that the best silent case is one with a completely open hole in the front for an intake fan. This is quite acceptable if the fan is very quiet and smooth, and if the internal components are equally quiet. But an open vent allows noise to go directly out of the case to the users' ears, so in most cases, some baffling is useful. The front bezel can act as a baffle that forces sound to travel around angles so that it loses intensity before exiting the case, while still allowing unrestricted airflow. A similar arrangement for back panel vents would also be useful, but less so, as the back usually faces away from users.

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.

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. 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.

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 Media PC use generally need to look nicer because most Audio / Video gear looks nicer, and most people want the PC to match cosmetically with other AV gear.

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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Reference|Recommended - Article Index
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