The base consists of two soldered pieces made of copper that host four heat pipes which pass through the pieces and that are also soldered to guarantee a perfect thermal conductivity between the parts. Both the base and the pipes are nickel plated, which apart from unifying the appearance of the surfaces protects the copper. Although the nickel's thermal conductivity is not comparable to that of the copper, it is not necessary to worry about the resistance it offers to the heat passage as the layer is so thin that practically there is no thermal variation. 

The heat sink is provided also with 52 aluminum fines of a very specific design which, far from being something merely aesthetic, gives it splendid aerodynamic characteristics since it obtains a low resistance to the air flow, and, as a result, achieves a high volume of air, which at the same time produces an excellent convection between the fines and the air that passes through, without entailing a beyond-the-tolerable noise level.
 

Speaking about size only, the Ultra-120 is L63,5 mm x W132 mm x H160,5 mm, with a total weight of 745g (fan not included). It is evident that this heat sink is neither small nor light, but it is not intended for every PC either. For those users who are considering the Ultra-120 as an option, efficiency is more important than size, so we don’t think this to be an obstacle. Of course, if someone decides to install the Ultra-120 inside a small case, it would be necessary to take precautions since it may cause some assembly problems, even when trying to close the case. But again, we doubt this heat sink combines well with a small low-end case.
 

Before analyzing the Ultra-120 more in detail, let's see how the heat pipes work. This will make us understand better the design of this type of heat sink.

Heat Pipes

In a very simplistic language, it could be said that the heat pipes are just pipes that carry heat. This is not wrong, but we’d be putting aside the most interesting part that is the physical principle that brings them to life.

Shall we review some physics? Everybody knows what a fluid is. An element may be liquid or gaseous depending on the conditions.

There are 3 parameters to take into account when working with fluids: pressure, temperature and volume. With these parameters it is possible to determine the state of a certain element. We all know that water, for example, is a liquid under normal pressure and ambient temperature, but if we heat it at 100ºC (also at normal pressure), it boils and then, after some time, it becomes steam.   

The boiling temperature of water or any other fluid depends on pressure and is proportional to it. This means that the higher the pressure, the higher the temperature necessary for the fluid to boil, whereas the lower the pressure, the lower the temperature required to produce the same event. Let’s store this in our minds for a while and speak about something else that is connected to this.

Back to the water, if we take its temperature since we start to heat it, it's possible to observe that it raises progressively until it begins to boil, and from that moment, it remains totally stable. It seems impossible the idea of heating something without any temperature change, but there is a change indeed: the water is evaporating and all the heat given to it without any temperature variation is actually 'consuming’ it when passing from the liquid phase to the gaseous one.

That’s a great amount of energy that seems to disappear but actually that energy is accumulated in the fluid molecules. That amount of energy is known as latent heat and it’s a property of each fluid in the same way as its specific weight, for example. This process works both ways; this means that the same fluid when going back to the liquid phase releases a large amount of heat, as a matter of fact, the same heat that was absorbed while evaporating.

Now let’s put together what we mentioned before about the relation between temperature and pressure in a fluid’s boiling point and the energy a fluid is capable of exchanging when changing from one phase to another and as a result, we’ll get the necessary information to understand what happens inside a heat pipe.

So, let’s get a hermetic container -the pipe in this case- and pour inside some fluid such as distilled water and then reduce the pressure to less than 1 atm (the selected fluid and the inner pressure will depend on the temperature range the heat pipe is going to work). Next, we introduce a material to give the pipe a ‘structure’ to work as a capillary net (very small tubes) and finally, we'll have all the elements to move great amounts of heat from one end of the pipe to the other.

Due to the low pressure inside, if any part of the pipe is heated, the water will evaporate fast and the generated steam will be displaced at high speed within the capillary net. The same steam will arrive soon at one end of the pipe, and if we are careful enough to keep that end properly cooled, the steam will condense, releasing the heat absorbed in the opposite end. In this way, a flow is created in which water is displaced to the hotter end, then evaporates and finally returns to where the cycle began, repeating it indefinitely.

This process occurs so fast that the ‘heat conduction' of the pipes is greatly superior to the best known conductor.

If you wish to read more, we recommend some theory guides we wrote on this subject.  

http://www.tortugahard.com/foro/viewtopic.php?t=549&highlight=pipe  

http://www.tortugahard.com/foro/viewtopic.php?t=428&highlight=pipe