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It was decided from the outset that this system would be built to run entirely
fanless, but that fan options would be included in order to test their effects
on system noise and system temperature. This picture above shows a Zalman fan
bracket attached to 2 Panaflo fans. The top fan is positioned to blow on the
CPU heatsink, the bottom fan is positioned to blow on the hard drive located
on the floor of the case. Each of these fans is attached to a Zalman FanMate
resistor device, and each will run at the lowest voltage which the FanMate would
provide and essentially the lowest voltage at which the fans would start. Fan
voltage could be controlled with the FanMates, which were positioned outside
the back of the case. In addition, the power supply for each fan could be switched
on or off from outside the case, allowing instant assessment of the contribution
of each (and both) fans to system noise and system temperature.
This picture shows the Barracuda IV suspended in its mounting frame on the
floor of the case (red arrow). 6-point attachment makes significant displacement
of the hard drive very unlikely. The frame is fixed to the floor of the case
with 4 mounting bolts.
Near the top center of the case, the white Radio Shack thermometer which measures
case air temperature is seen just above the RAM sticks. The thin black wire
just left of that thermometer is the Compunurse thermometer that is placed between
the heat sink and the cpu. (Note: That thermometer is not on the heat spreader.
That placement would wreck the thermometer and possibly the cpu. The probe sits
in the gap between the heatsink and the heat spreader, and touches the edge
of the heat spreader.)
The VIA C3 Ezra is specified for operation with CPU case temperatures in the
range of 0°C to 70°C. VIA recommends external CPU case temperature be
measured by attaching a thermocouple to the center of the VIA C3 package, as
the heat produced by the processor is very localized so measuring the case anywhere
else underestimates the case temperature. This requires drilling a hole through
the base of the heatsink and epoxying a thermocouple so that it is positioned
at the center of the CPU when the heatsink is mounted.
Whether my thermometer probe position is valid is open to question. This point
is moot as I don't have a thermometer that uses the kind of thermocouple which
would make a true core temperature reading possible. Suffice it to say that
the temperatures I report may be a few degrees lower than would be obtained
at the absolute center of the CPU. Still, virtually all reports of other measurement
techniques seem to be 2-15°C too low compared with CompuNurse-type thermometer
The rounded IDE cables are very nice, a great improvement since they are easy
to position, much less vexing than ribbon cables. They also decrease clutter
and probably aid air flow.
This picture shows the position of the 2 Panaflo fans (artifically highlighted
and marked with red arrows) in their modified Zalman bracket. The upper fan
blows on the CPU heat sink, the lower fan blows on the Barracuda IV hard drive.
This is the configuration of the computer at the end of the project. The side
panel was later put back on the case, returning it to nearly the same external
appearance it had before any modification was done.
This is the fan controller. It features an off-on switch for each
fan. There is also a variable resistor for the hard drive fan. Since each fan
is supplied with an out-of-the-case FanMate, there is no need to use the variable
resistor, though. This controller sits on the top of the case, although I could
put it on my desk or in any other convenient spot.
This is the schematic for the fan controller. It might have been clearer if
I had made a circuit diagram, but this seemed to be the most widely accessible
approach. My general approach to these projects is to plan for everything to
go horribly wrong. So, I never work on components: I work on extension cabling,
which is cheaply and easily replaced. All connections are made with hot-joint
solder and covered with shrink tubing. (My local electronic parts store wants
to give me a Platinum Card.)
PERFORMANCE and CONCLUSIONS
This set of CPU temperature observations was made with variation in CPU fan
voltage, under varying CPU load. The 7.4 volt reading came from testing the
FanMate on my workbench, with the resistance at maximum. [Mileage may vary.]
The hard drive fan was left off at all times. The lesson here is pretty clear:
Going fanless is a possibility with this system, but at high processor loads
the CPU gets hot. The rated maximum temperature for this CPU is 70°C. In
fact, during fanless drive partitioning and formatting, CPU temperature reached
73.8°C. Although the CPU showed no signs of strain, this heating is probably
not a good idea.
Please remember that VIA said only that the CPU could run fanless. It was never
said that the whole system could run fanless. Convective cooling in a mostly-closed
box is not very efficient. Even a slight amount of air movement makes a substantial
reduction in system temperature.
When the hard drive fan is also running, there is an additional 2-5°C drop
in CPU temperature. Hard drive temperature also stays down nicely, being routinely
less than 42°C.
The case air temperatures tell a very interesting story. It is doubtful that
much air is moving through this case with the current fan positioning. What
is probably happening is that the heat from components is being spread to the
1.5 cubic feet (35,000 cc) of air in the case. The cooling power of this volume
of air is substantial, and the key goal in system cooling becomes elimination
of tiny areas of air stagnation in regions of substantial heat generation. This
is why the low-voltage Panaflo fans make a big difference.
It goes without saying that this analysis only holds for systems which are
not generating much heat, and for environments in which room temperature is
This review is the first computing work that I have done on the system which
is being described. During preparation of this piece tonight, room air temperature
has been 23.3°C, CPU temperature 36.5°C, case air temperature 33.0°C
and hard drive 39°C. Both Panaflo fans have been running, and they are inaudible
from my chair. Absent the power-on light, I could not tell that this computer
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