Closer Look At The Heatsink

SFF system designs are pretty customised. Therefore, a regular cooler that is built specifically for an ATX case layout may not perform as well as it would if installed in an SFF system. The same applies to the S-presso.

Consequently, ASUS has included their own heatsink and fan specifically designed for the S-presso.

The ASUS S-presso heatsink fan solution

The heatsink is made up of aluminum fins and a shroud, a copper base and two heat pipes conducting the heat up to the fins. It's almost a must for the base a heatsink to be made of copper these days, since copper draws heat from the processor faster than aluminum.

This is very important in view of the fact that Intel Pentium 4 processors today can generate up to 100 watts of heat!

Check out the fins

Taking a closer look at the heatsink design, you can see that the aluminum fins are slightly folded and welded onto the copper base.This, of course, does not provide the best possible heat transfer from the copper base and up to the fins. That is where the two heatpipes come in.

In this heatsink design, the heatpipes help the transfer of heat from the copper base up to the fins! Therefore, there is no more issue of efficient heat transfer between the base and the fins.

Heatpipe are used to help transfer heat from the base of the heatsink to the fins

Also, take note that the two heatpipes transfer the heat to two different heights in order to help distribute heat more evenly, thereby preventing hot air from overlapping too much as it travels across the fins of the heatsink.

How A Heatpipe Works

The heatpipe contains a certain kind of liquid that easily vaporizes within it. The heat pipe is generally divided into two sections - the evaporator section and the condenser section.

The evaporator section is placed at the source of thermal output. The heat absorbed by this section boils the liquid, turning it into vapor. The vapor then travels upwards until it reaches the end of the tube which is attached to the heatsink.

The heatsink dissipates the heat and the vapor condenses back to its liquid form and travels back to the evaporator section at the bottom of the tube. This cycle repeats as long as there is a difference in temperatures between the two ends of the heatpipe.

For a illustrated explanation, check out the following diagram, courtesy of Heat Pipe Technology, Inc.

A traditional heat pipe is a hollow cylinder filled with a vaporizable liquid. A. Heat is absorbed in the evaporator section. B. Fluid boils to vapor phase. C. Heat is released from the upper part of cylinder to the environment; vapor condenses to liquid phase. D. Liquid returns by gravity to the lower part of cylinder (evaporator section). Source: http://www.heatpipe.com/heatpipes.htm

Another interesting feature of the heatsink is the location of the fan. Instead of the conventional top position, the S-presso's heatsink has its fan on its side. This is to enable it to draw cool hair efficiently from outside the case, through the fins and finally out the exhaust fan at the back.

The shroud, of course, provides a consistent airflow through the fins.

Fan installed on the side to blow air through the fins vertically

The fan used by ASUS looks like a thin-profile one with a lot of fins. These fans usually provide good airflow, even at low speeds, but is not able to create high-pressure airflow to the fins. However, as the fins of the heatsink are not dense enough, pressurised airflow is not required for it to work efficiently.

The picture below shows the silicon-based thermal pad that ASUS incorporated into the base of the heatsink. So you won't need to get yourself a tube of thermal paste to get yourself started.

However, for best performance from the heatsink, simply wipe the thermal pad clean and apply a thin layer of Artic Silver!

Bottom of the heatsink

The copper base does not look smooth at first sight, and it definitely does not have a mirror-smooth finish. However, looks can be deceiving: the base is smooth to the touch. But then again, perhaps our fingers are not sensitive enough to detect microscopic edges. So, some further lapping of the heatsink base might be helpful here.

Of course, we shall see if this is useful when we test the system for overclock-ability. Otherwise, even stock cooling will be enough to keep things cool and running fine.

Now that we've taken a look at everyting else, it's time to move on to the main item of this review; The ASUS S-presso S1-P111 itself!