[mythtv-users] My perfect HTPC

[Brian Wood]

On Thursday, October 07, 2010 10:42:07 am David Lasker wrote:
> On 7 October 2010 11:24, Josu Lazkano <josu.lazkano [at] gmail> wrote:
> > I have this box in mind:
> > 
> > Thermaltake Element Q case:
> > http://www.newegg.com/Product/Product.aspx?Item=N82E16811133093
> 
> There are several similar but lower-cost cases that are nearly identical to
> the Thermaltake Element Q, including:
> 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16811154091
> http://www.newegg.com/Product/Product.aspx?Item=N82E16811147131
> http://www.newegg.com/Product/Product.aspx?Item=N82E16811154093
> 
> Newegg calls these cases "mini tower" while the Thermaltake is a "desktop";
> I have no idea why. They can be used either horizontally or vertically.
> 
> These cases are not completely fanless. They rely on the PSU fan, which has
> an air intake directly over the CPU, and exhausts hot air out the rear of
> the case.
> 
> The internal drive bay mounts a hard drive on its side at the right side of
> the case. If you also use a PCIe card on the left side of the case, then
> airflow into the case will be very constricted, and your system might run
> too hot. If you mount your hard drive in the external drive bay, located
> under the optical drive bay, and leave the internal bay unused, then you
> should get sufficient air intake for an Atom board.
> 
> I used the Rosewell N82E16811147131 case for a home server (not for
> MythTV), and I am very happy with it. The PSU supplied with the case has a
> variable speed fan. When it is cool in the room, the fan is nearly silent.
> However, when it is hot in the room, the fan noise is very noticeable,
> probably too loud for an HTPC. If you decide to go with Atom/ION, you
> might want to consider using a board with an external brick power supply
> like ASUS AT3IONT-I Deluxe, or else get a PicoPSU.
> 
> Hope that helps...


Sometimes the stock fans can be replaced with quieter ones, if you can find them. A simple change of blade shape can have a 
large effect on the generated noise.

There is a HUGE difference between no airflow and "just a little bit" of airflow. With no airflow at all, the inside of the 
case just keeps getting hotter the longer the machine is on.

Completely fanless machines have to rely on convection currents created by the heated air in the case. Such a case is very 
difficult to design, especially when you do not know precisely what devices will be put inside it, and how much heat each 
will create. In fact, I would say it is impossible to design such a case without knowing exactly what it will contain.

Tactics like spinning down drives, clocking down CPUs or using SSDs, will certainly minimize the heat that has to be 
removed, but having a quiet fan, turning at a slow speed, is probably the best approach, unless "exotic" approaches are 
taken, using many heat pipes, external cooling units or the like.

It's a simple math problem, you have to remove heat at least as fast as it is generated, so the only approaches are to 
generate less heat, or remove more.

Usually it's the simple things that are the hardest to implement. The few cases available that were actually designed by 
thermal engineers are made using assumptions about what is contained that may not be realistic, especially for 24/7 Myth 
systems. Most cases are designed by industrial designers who wouldn't know what heat load really is, or how to measure it. 
Many such designs are about as effective as tail fins were on 1950s automobiles, they sell product, but don't improve 
performance.