The "Mass-Air" heatsink system
consists of a high performance Alpha heatsink, a custom formed aluminum
air duct, and two mounting screws with preload springs.
For this test a ATI Radeon 9700 Pro video
card will be used. The small stock heatsink uses a high-speed fan for
cooling. Although the heatsink works ok, the fan is too noisy for HTPC
use.
To remove the stock heatsink, detach the
hold-down pins. The pins consist of two piece plastic parts, a outer
bullet-nose step peg and a inner locking pin. To detach the pins, pull
the inner pin out as shown above. After both locking pins are pulled up
you can use a small screwdriver to carefully push the stepped peg out
from the bottom side of card. Now you can lift the heatsink off the
card.
With the heatsink off, clean the processor
chip on video card with isopropyl alcohol. Some of the thermal pad may
still be stuck to the chip.
The plate around the chip is to help support
the heatsink and does not transfer much heat. Most of the heat is transferred
from the top of chip to the bottom of heatsink. The gap between the
heatsink and chip is .002". A adequate layer of heatsink compound Artic
Silver or a thermal pad must be used on top of chip. Do not apply
thermal compound to the support plate as this will increase the distance
between chip and heatsink making heat transfer less effective..
The high performance Alpha heatsink uses a
copper heat spreader to distribute the heat evenly into the aluminum
fins. The fins are very thin with wide spacing between each fin. This
decreases the pressure drop across heatsink and allows for high volume
airflow.
The heatsink is held in place by two pre-load
screws. Each screw has a nylon washer to protect the backside of circuit
board. The precision coil springs apply equal pressure to the chip
support and allow for expansion and contraction of the heatsink. To set
preload, simply tighten the locknuts until the end of screw is equal to
the top of nut.
Heatsink installed on card and ready to mount
into computer. The heatsink and air duct clear all components on the
card.
The large air duct allows for a unrestricted
flow of air across heatsink. The case must have negative back pressure
for this system to work. Negative back pressure can be achieved by using
exhaust fans to blow hot air out of case. Cool air is drawn in though
the intake ducts. If intake fans are used, make sure they are smaller or
flow less than the exhaust fans.
Mass-Air heatsink system installed in case
with the air intake duct. The large heatsink and air duct occupy the PCI
slot adjacent to the video card.
Test System:
Case: The Heatsink Case
Power Supply: 2U 350 watt
Motherboard: Asus P4T533
CPU: Pentium 4 2.26MHz
CPU heatsink: Alpha PAL8942 with Sanyo Denki 80x15mm fan
RAM: 256MB, RIMM 4200, 32-bit RAMBUS
Video Card: ATI Radeon 9700 Pro
Sound Card: M-Audio Audiophile 2496
DVD Drive: Pioneer DVD-106S
Hard Drive: Maxtor Diamond Max Plus 60GB
Testing Parameters:
I ran each heatsink for one hour to stabilize temperatures. Case fans
were connected to a automatic speed controller which adjusts fan speed
based on temperature at the sensor. The controller sensor was placed in
front of case fans to monitor the air exhausting from case and the air
above nearby CPU. To monitor the actual graphics processor chip
temperature, I placed a sensor on the backside of video card in the
center of chip location. To measure the internal case temp, a sensor was
placed above the motherboard between the CPU and face plate. The MB is
equipped with a built-in temperature sensor and another sensor is built
into the CPU. Digital temp sensor probes were placed inside the power
supply and outside of case to measure the ambient air. I used Motherboard
Monitor 5 for reading the fan speed and temperatures. For testing
full load conditions, I used Hot CPU
Tester and Motocross
Madness 2. I found running Hot CPU Tester generated the highest
temps all around, so I used that test in my results.
Results:
Comments:
The Mass-Air Heatsink system not only reduced GPU temps slightly, but
also reduced MB, CPU, and Case temps significantly. This was primarily
due to the added airflow across video card. The stock ATI heatsink/fan
tends to re-circulate hot air from around the card. Having constant
airflow over the card allows the heat to be exhausted through the case
fans which lowers all internal temps.
The linear flow of air across the heatsink fins on the Mass-Air does
a good job of extracting the heat from the GPU. I tested the heatsink
without the air duct in place and the GPU temps immediately rose higher.
Other passive heatsink systems on the market do not introduce airflow across
the fins, this greatly reduces their effectiveness.
Another benefit of lower overall temps is that the case fans ran at
slower speeds reducing noise. At idle, with the Mass-Air HS, the case
fans were only running at 1520 RPM. The fans are practically inaudible
at that speed. The fan speed was being controlled automatically by the Fan
Speed Controller.
