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A steady trickle of fanless cases have tempted silence-seeking PC users over
the past decade. The basic concept with almost all fanless cases is simple:
Turn the external casing into a big heatsink which conducts heat from components
by direct contact or via heatpipes, then disspiate the heat into the air with
natural convection. Most often, the case is made from aluminum, a better conductor
of heat than steel. Some of these cases have been massive and heavy, like the
now discontinued Zalman TNN
series, in order to accommodate hot gaming components. Others have taken
the minimalist approach, using cooler running components so that there's less
heat to dissipate, allowing for a smaller, less costly product.
Today, CPUs with extremely low thermal design power (TDP) that run under 10W
at idle, and automated dynamic clock/voltage features make passive cooling relatively
easy, at least with some CPUs and big heatsinks. In combination with higher
performance motherboard- integrated video cards, a completely fanless PC is
a lot more practical than in the past. However, fanless operation of a higher
power system (such as the typical gaming rig) still remains a challenge. Fanless
devotees should be aware that components such as the voltage regulation module
on the motherboard, and similar power electronics in video cards are designed
with the expectation of at least some airflow across them. Even in a very low
power system, eliminating all forced airflow usually shortens component life.
Two HDPlex H5 fanless "heatsink cases" in silver and black.
Spinning hard drives and electronic noise from power components
have also been challenges for fanless systems.
The best approach to quieting a HDD is to mechanically decouple it from the
case so that its vibrations don't excite the large thin panels of the case and
cause noise. This means "float" mounting the HDD in an elastic suspension
or soft rubber bushings or grommets. In a conventional case, the slight loss
of cooling via conduction can be compensated with directed airflow from quiet
fans. But in a passively cooled case, this is much more difficult. The increased
availability of high performance, silent, solid state drives at much more affordable
prices in combination with inexpensive high capacity network attached
storage (NAS) has made HDD noise much less of a problem in recent years.
With solid state prices plummeting, it is routine now to load the Operating
System to an SSD, and use a large quiet SSD for storage. Better yet is a large
capacity SSD for storage, but this is still a pricey proposition. A good performance
NAS located remotely on a gigabit network can be nearly as fast as local HDD
storage. This eliminates the need for large storage in the local PC while offloading
both the power and noise of large HDDs to a distant closet, basement or attic.
The high pitched whining and squealing of power electronics has usually been
masked in the past by the whooshing and whining of high speed fans, but in a
system with very quiet fans or no fans at all, such electronic noise can become
quite annoying. While electronic noise can usually be avoided by staying with
high quality components, it is sometimes caused by interactions between power
circuitry and a particular component or combination of components. In such cases,
trial and error replacement of offending parts is usually the only solution
for DYI builders other than re-introducing a whooshing fan. Judicious
use of glue from a hot glue gun to physically damp coils and caps is a fairly
common practise in manufacturing, but there's some risk of potential damage
for the DIYer.
The Aluminum is Cooler Myth - Some favor aluminum cases, citing an ability
to better cool components mounted within. This is a myth. No heat producing
component benefit in any significant way from being inside an aluminum case
unless the components have a direct conduction path to the case panels,
a feature usually found only in a few cases meant for fanless cooling. The only
heat producing devices that are normally mounted in direct contact with a case
are the drives, particularly the hard drives; the difference between aluminum
and steel in this application is insignificant.
The Potential Aluminum Drawback - Aluminum cases tend to pick up hard
drive and fan vibrations more readily than steel cases, and make a more audible
humming or buzzing sound. This quality is related
to the density of aluminum: It has only about 30% of the density
of the cheaper, more commonly used steel. Hence,
aluminum panels must be thicker than steel panels to achieve the same
resistance to vibration. Internally applied panel damping materials
(especially the heavier kinds) appear to damp the resonance down fairly effectively,
but it can be difficult and expensive to eliminate entirely. Internal supporting
cross braces that effectively divide the large panels into smaller ones also
help quite a lot because smaller panels are more rigid, stiffer, and less prone
to lower frequency vibration than larger ones.
This does not mean aluminum cases cannot be used to make a silent computer,
just that there are disadvantages with them when compared to similarly constructed
steel cases. Regardless, many aluminum cases certainly look nice, and can be
made very quiet. Also, many hard drives are now so quiet and vibrate so little
that the acoustic difference between aluminum and steel cases is becoming less
significant, except when panels are very thin or not rigidly assembled.
Aluminum / Steel Combo - Some case makers have sought to combine the
desireable look of aluminum with the sturdiness of steel by using a front facia
or bezel made of aluminum on a steel chassis. The Silverstone
GD05 and the Coolermaster Sileo 500
are examples of this type of hybrid case.
Simulated Brushed Aluminum Plastic - A trend that began around 2012-13,
the faux brushed aluminum front panel is made from plastic, and offers
the look of black anodized brushed aluminum at much lower cost. Naturally, it's
been adopted by legions of case makers, particularly in the lower tier. In general,
plastic panels don't offer better acousitc damping than thick aluminum. Whether
it is convincing depends on who is looking.
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