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NEW FAN TEST SYSTEM
There are two parts in our fan testing system. One part concerns audio measurements,
the other involves cooling performance.
A. Audio Instrumentation and Resources (fully detailed in New
Audio Test Gear, SPCR 2008) -- Our audio measurement tools are now far
more sophisticated than before; it is SPCR's anechoic chamber and 9dBA-capable
instrumentation. We can assess not only the SPL of a fan at different speeds,
but also its frequency spectrum, so that tonal peaks can be identified and visualized.
ACO Pacific 1" diaphragm capsule mic with adapter on 1/2" preamp.
M-Audio FireWire 410 atop M-Audio Tampa digital mic preamp.
B. Fan Test Gear -- Our latest airflow measurement device (anemometer)
is by far the most accurate of the handful that we've acquired over the years.
It is used not as a primary tool, however, but a secondary one. Our approach
this time around is not to be concerned about airflow per se, but its
thermal effects in a cooling system. CFM is relegated back to its original place
when we first began assessing fans years ago: Mostly a point of note. Our
most important measured parameter is temperature rise, not by itself but plotted
- i7-1366 CPU die simulator with embedded T-type Thermocouple wire
6030D DC Regulated Power supply, 0-64V/3A
- Custom built 0-12VDC Regulated Fan Controller
- Kanomax 6803 Anemometer
- Mannix DT8852 Dual Input Thermometer (K, J or T Thermocouple input)
- High accuracy general purpose Multimeter
- Laser digital tachometer by Neiko Tools USA
- Calibrated electronic strobe light (alternate tachometer)
This is our fan testing setup as of May 2010.
(Cick on image to enlarge.)
The i7-1366 CPU simulator, with T-type thermocouple wire embedded. Blue
wires are used to power the heater coil in the copper block. The mounting
block is a piece of phenolic resin (like Bakelite), which has high heat
A Thermalright Ultra 120 Extreme heatsink is employed. It has roughly
middling airflow impedance (resistance to airflow), and an excellent mounting
system that ensures highly consistent pressure from one heatsink sample
to the next, from one installation to the next. IC Carat Diamond thermal
interface material was used between copper block and heatsink base to
ensure maximum heat transfer.
This is the casing of a Shuttle Zen PC, gutted to squeeze in an FSB 300W
ATX12V PSU and a Sunbeam 4-channel fan controller. The Sunbeam is unusual
in that it allows the voltage to be varied from maximum to 0V. The 12V
output of the PSU has been tweaked up to nearly 13V, in order to compensate
for the voltage drop through the fan controller. The fan in the original
PSU has been removed; it is not needed for the tiny loads of 12VDC fans.
A separate multimeter is used to set fan voltage.
A Mannix DT8852 Dual Input Thermometer keeps track of temperature at the
top of the simulator CPU die, and of the intake air 6" in front of
the fan; the difference between these two temperatures is key. A Mastech
6030D DC Regulated Power supply can provide up to 64V at 3A. 137W was
chosen to be the standard load. The calibrated strobe is one of the several
tools used to measure fan RPM. An infrared tachometer is another.
The Kanomax 6803 Anemometer came supplied with a super low friction calibrated
Pacer 275 vane probe. This is a high precision tool; the tiniest bit or
airflow is enough to get the vane spinning. Airflow is measured in FPM
(feet/minute) directly at the intake side of the fan, while it is mounted
on the heatsink. The highest sustained value is recorded for each speed.
The foam harnesses used in earlier fan test are still used for acoustic
measurements and recordings. We tried doing this while the fan was mounted
on the heatsink, but there are just too many interactive results caused
by the rattling or buzzing of the fins on the heatsink. The foam harnesses
minimize such effects; you can say, generally, that the recordings of
the fans represent them at their best or quietest... although in a few
odd exceptions, some fans sound better mounted on the heatsink.
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