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Thermaltake's
SubZero4G unit utilizes thermo-electric cooling at
a level which poses little threat to the computer
itself. For those of whom do not understand the technology,
thermo-electric coolers are composed of two parts.
The first part, the power supply, typically draws
power directly from the wall and converts it to 12
volts. The output power flows through a peltier (sometimes
referred to as a TEC), which under current draws heat
from one side directly to the other. When attached
to a heatsink as is the peltier in the SubZero4G unit,
heat will not dwell on the heated side of the peltier,
instead it flows through the aluminum pins and is
transferred into the air flowing between.
Because the thermal conductivity of a peltier unit
(ceramic) is much lower than that of copper, Thermaltake
placed a coldplate between the CPU and the peltier,
allowing heat to be distributed evenly along the surface
of the peltier, effectively enhancing the efficiency
of the unit on the whole.
A question which commonly arises is "How can strapping a heater onto a CPU make it colder?" The answer is found through simple common sense. The peltier unit has one hot side and one cold side. When not attached to a heatsink, the cold side will not get any cooler because the hot side can't expel its heat efficiently on its own, just like a CPU. The peltier will turn into a heating unit and burn up. When attached to a heatsink, the peltier cannot get hot because the heatsink is much more efficient at giving off heat. This allows the cold side to stay cold and cool the CPU more effectively than a standard heatsink.
Typical DIY(design-it-yourself)ers will tell anyone interested in peltier cooling to use no less than a 220 watt peltier. This kind of power lowers CPU temperatures easily below -15C and generates a lot of condensation in the form of frost around the CPU, the motherboard, the cold plate, and peltier. This is a bad thing. The Thermaltake peltier uses at maximum output 75 watts, which means even the coldest parts of the peltier should be above air temperature at all times and water will not condense. Just in case things do get a little chilly, Thermaltake installed a temperature probe directly inside the cold plate, in case the coldplate temperature drops below the air temperature (monitored in the power supply, might we be led to assume). The fan speed is regulated as is the peltier voltage. A 'power mode' is available by pressing the preconnected button switch which only appears to turn fan speed from regulated to constant full power. Changing the power through the peltier seems to be completely up to the power supply so as not to cause accidental condensation problems. Another obstacle Thermaltake cleared was the power supply switching on and off in sync with the system. This was solved by installing the power supply directly into a PCI slot, and by pressing the power button on the case, the power supply turns itself on too! This way power is not wasted cooling an idle chip, dropping temperatures and creating condensation. Thermaltake also took the liberty of providing a 12V molex connector for attaching case fans. When attempting use of the blue LED fan, I found it flickered, and when asked to give an estimate of how fast I would guess 30Hz. While I wouldn't want all my LED fans flickering I wouldn't have a problem connecting standard case fans to such a device to decrease volume at the same rate as the CPU fan.
A first glance at the SubZero4G heatsink brought
back memories of the older Volcano 6cu+ I used for
about six months of my adolescence. It was horrible
for overclocking, and came equipped with a vocal 60mm
fan pushing low airflow. Needless to say it was quickly
replaced with a better heatsink with more, smaller
fins, a better finished base, and an 80mm fan. That
heatsink was in turn replaced with a pure copper heatsink
with smaller fins, which in turn had its day and so
on....until I received the SubZero4G. The strange
part was how such a heatsink could carry such a hype
about it. The fins are easily five times as thick
as those on the Thermalright SLK-800-U ((as
reviewed here)) and made of aluminum. How could
it possibly compete? The answer is all about volume.
Heatsinks like the SLK-800-U may be more powerful
than the Thermaltake, but tight fin designs require
exceptionally high amounts of airflow for reasons
not easily described without a teaching degree. Read
the review if you want evidence. The Thermaltake heatsink
design is for high temperature loads and low speed,
low volume fans, so this is why it should be able
to handle a CPU load as well as a 75 watt peltier
without an 80cfm monster of a fan.
The largest precaution to using such a high powered device would be ensuring efficient case cooling. No standard beige case could handle a full load of 200 watts as well as the 75 put out of a SubZero4G cooler. Chenming's full tower design, adopted by Thermaltake to create the Xaser series, made an outstanding candidate for good airflow, with three intake and three exhaust fans pushing a total of 180CFM through the case at all times. This is why testing will be conducted with a (slightly modified) version of the XaserII steel case, to create optimum case airflow. Presently, the only real difference between the stock and the modified case that will affect the cooling performance of the said unit, will be the two 80mm front intake fans replaced with two 120mm fans, and the side door intake fan being reversed to an exhaust.
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