Comparison of coolers using heatpipes

Author: Aleksandr Mitrofanov
Date: 28/12/2003

Fire, water and brass horns

As you can guess from the title, today we are going to cool today's hottest processors ("Fire"). That is surely Pentium4, which has a heating power of 100W. And this value can increase after new processors on new Prescott kernel are issued. It is clear that standard aluminum coolers are absolutely ineffective for this. That is why manufacturers are searching alternative methods of cooling, two of which are examined in this review. The first one is Poseidon, the system of liquid cooling; and the second is using of heatpipes (brass horns).

A couple of words about heatpipes. The main goal of a heatpipe is to conduct heat from one end to another. Generally, heatpipes are made of brass and contain easily-boiling liquid. Inside a pipe (from the side of the source of heat) the liquid evaporates and absorbs heat. At the opposite end, the liquid condenses if a radiator is applied to the pipe. In other words heatpipe is used for heat conduction and cannot cool a processor (or other heat source) itself. By the way, we have already reviewed similar cooling systems; these are videocard coolers Zalman ZM80C-HP.

Thermalright SP-94

Taiwan company Thermalright has a very interesting approach to business: it sells only heatsinks. That is a user must install fan himself according to his own taste. The heatsink is supplied in a big cardboard box.

Thermalright SP-94 Box Thermalright SP-94 Inbox

It must be noted that all the components are thoroughly packed in foam-rudder to prevent possible damage during transportation.

Besides the heatsink itself, the package contains a bracket, a slab and a syringe with thermal paste and a bracket for a fan. First of all we will look at heatsink design.

So on a brass base there are more than twenty brass ribs. For faster heat conduction, three heatpipes are built in heatsink's base.

Because of that, each rib touches a pipe with rather big area. In order to achieve this effect, each rib has special petals, which fold a pipe. Besides that, between a pipe and a petal, there is a thin coat of thermal interface, which also improves heat conduction.

Contact between ribs and heatsink base is made with the same quality. Each rib is inserted into a special slot in the base. Besides that, ribs have small platforms, which touch upper side of the base. Thermal interface is actively used here.

As the result we can make the following conclusion. Although ribs and basement are not monolithic, the effectiveness of SP-94 heatsink does not concede the effectiveness of monolithic heatsinks.

Concerning the base, its quality is very, very good. Like on the majority of good coolers, there is a protective film on the base, which is removed just before the installation of the eatsink. By the way, installation of the heatsink is a time-consuming process and an ordinary user can consider it difficult. Especially if we take into account the lack of an installation manual in the package as well as on the company's site.

However this product is designed for overclockers and similar "advanced" people, which can do it themselves. So the first step is the removal of attaching frame from the motherboard. To do this we are taking out plastic pins and then remove the frame with pliers (or with strong fingers).

Our next step is the installation of the plate. In the center of this plate there is a rubber backing, which prevents short circuit. For this we are passing special pins through holes of the motherboard and tighten them. It is not necessary to tighten strongly, several turns is enough.

One can optionally put plastic insertions under hobs. The package contains them. In the next step we are salving thermal paste (I used KPT-8) installing the heatsink and looking at the imprinting.

If all pins are tightened evenly, the processor imprints completely.

Then everything is simple: we are inserting springed bolts and screw them chock-a-block.

There are extra details after the installation, but don't worry, they are spare.

The next step is installation of a fan. For this we are taking an appropriate fan and fix it with the wire frame.

92mm fan Titan

It is allowed to install 80mm and 92mm fans onto SP-94 heatsink. Which fan must be installed: noisy and productive or quiet is the user's responsibility. I used 92mm Zalman ZM-F2 fan with ~2800RPM rotation speed and ~36dB noise level for testing.

The preliminary conclusion is that SP-94 heatsink appears to be good and effective product, which will interest mostly overclockers. Installation procedure seems quite simple (it is not necessary to think much), but rather time-consuming.

Auras CoolEngine-T6C (Golden)

Here we have two coolers of an absolutely unknown manufacturer on Russian market, the Auras company.

Both coolers are designed for Pentium4 processors and have identical structure. They differ only in fans. Besides that, one of the coolers is colored in gold, that is why it is called Golden.

The particular feature of CoolEngine-T6C cooler is that the fan is located not horizontally (as on the majority of coolers) but vertically.

It creates air blast of 33.7CFM, which cools brass ribs. By the way, the ribs are located unusually, that is horizontally.

From the cooler's base there go two heat pipes, which thread through all the ribs. As on the Thermalright SP-94 heatsink, on Auras heatsinks holes in each rib have embossed platforms, which are used to hold heatpipes. This fashion allows to achieve high efficiency of heat conduction.

If you look at the cooler from a side, you will see a metal case, which is used to strengthening cooler's carcass, as well as to direct air blast. The box is attached to the base with clinches. By the way, cooler's base is a this brass plate with a good quality of treatment.

This plate is inserted into another one which is made of aluminum. The latter one also has ten short ribs, which also take their part in heat conduction.

Now we will review a fan more precisely. It's rotation speed is 3800RPM and it's noise level is 32.3dB. Subjectively noise level is rather high and if I were a buyer of CoolEngine-T6C I'd replaced the fan for a more quiet one (or switched it through a rotation speed regulator).

Now a couple of words about the Golden version. In fact we have the same CoolEngine-T6C cooler but equipped with other fan and colored differently.

I couldn't figure out actual characteristics of the fan.

Subjectively, the noise level is even higher than of T6C, but Golden model has an important benefit. The fan is made of transparent plastic and blue LEDs are installed in corners. As the result the cooler is covered with beautiful blue light.

The preliminary conclusion is that the structure of the cooler looks effective. The only drawback which I can accentuate is the high level of noise.

Poseidon WCL-02 (èëè Iceberg 1)

We have tested Poseidon water cooling system, made by Korean company 3RSystem. Besides that, this system is being sold under Iceberg 1 trademark (however, reverse situation is possible). This product appeared on Russian market in the beginning of 2002 and has conquered an empty market segment of high performance cooling systems.

Of course at that moment many enthusiasts used self-made water cooling systems. But an ordinary user could only dream about quiet and at the same time effective heat conduction.

The system is supplied in a big cardboard box, all its components are packed thoroughly.

I have to tell particularly about the user manual, which describes installation procedure in detail. However, we won't consider this question circumstantially because this product has already virtually disappeared from sale. The reason is too high price, at the moment of its uprise Poseidon WCL-02 costed more than $100 (with a prime cost of approximately $20-$30). For this quantity of money a user was buying aluminum waterbock, aluminum heatsink and fan, liquid reservoir and pump and a connection tube.

Just a half a year after that more effective systems with brass heatsinks and waterblocks started to appear at the same price. As the result they displaced Poseidon WCL-02 from the market.

An assembled system looks in the following fashion:

Surely, after the system is assembled it must work for some time outside a computer. After the complete testing on possible leaks it is possible to install the system into the computer.

As you can see, the system occupies very little room and can be easily placed into a standard ATX case.

I should say a couple of words about the waterblock: the quality of treatment was horrible. Everything you can see on the photograph below is the result of 15 minutes of polishing.

The waterblock has two kinds of bracings: a metal clip for AMD processors and a plastic cup for Intel processors. Everything is very clear with the clip (it consists of two parts), but installation is very difficult for Intel processors. So the waterblock is installed into plastic cup, which must be pinned by a plastic frame of a "box" processor (this is the only detail, which is not contained by the package). As the result, design looks very uncomfortable from assembler's point of view: as a rule a half of attempts fail and the plastic frame breaks.

And now a few words about the system in general. In spite of many insignificant drawbacks elicited at assembly process, the system works rather quietly. The only source of noise is an 80mm fan, which has a standard bracing. This bracing allows to replace it with a more quiet one. The pump works without noise.

A couple of words about the performance. I installed Poseidon system onto AMD platform and it has shown bad quality of cooling. For comprehension I will refer to the result of our old review:

The reason of poor effectiveness lies in the fact that AMD processor kernels contact aluminum waterblock directly. This leads to poor heat conduction at high charge, aluminum cannot conduct heat fast enough to decrease kernel temperature.

However such problem is partially away with installation of Poseidon WCL-02 on a system with Pentium4 processors, which have built-in heatspreaders (a brass plate). As the result, the area of heat exchange increases and the total effectiveness increases.

As the result, after modification of waterblock bracing,

a part of plastic cup is filed off and other type of bracing is used

Poseidon WCL-02 system was used in the majority of motherboard tests for Intel processors. And for more than 18 months I didn't have any problems with its impermeability or pump operation.

Testing

Testing was performed on Abit IC7-G ; motherboard, Motherboard Monitor was used as a monitoring tool. Intel Pentium4 2.4 processor with D1 stepping, working on 3.0GHz on nominal voltage.

Also all coolers were tested in more difficult conditions: the processor was working on 3.6GHz at Vcore=1.65V.

Heating of the processors was made by two running copies of BurnP6. Two working applications allow to load a processor at full capacity (I should remind that D1 stepping processors support HyperThreading).

Then the tested system has been assembled in Inwin S506 case and power supply has been placed outside the case. The matter is that this power supply has a fan with adjustable rotation speed (dependent on temperature) and such power supply could influence testing results. If a cooler has its own thermal interface, this thermal interface has been removed and further measures were carried out with KPT-8 silicon-organic thermal paste.

Here goes the effectiveness of Pentium4 3.0GHz cooling.

The system was working steadily with all types of coolers. Zalman 7000 cooler and Themalright heatsink + Zalman ZM-F2 fan have shown particularly good results. Water cooling system conceded them only 4 C degrees. The most probable reason is poor effectiveness of aluminum waterblock.

As to Auras coolers, their effectiveness can be ranged as average (close to Tt Spark5 cooler or Tt Spark7). The reason is relatively weak fan, which is installed on CoolEngine-T6C and -T6C Golden models.

Then we increase voltage up to 1.65V and increase FSB frequency up to 300MHz. Now Pentium4 processors is working on 3.6GHz and is emitting at least 100-110W of heat.

The first testing was performed with Auras CoolEngine-T6C cooler. The temperature reached the value of 71C quite fast and the system shut down a minute after that. That is why I decided not to test knowingly weak CoolEngine-T6C-Golden. Zalman 7000C was the next: the system was working with him for 10 minutes with a processor temperature of 70C and then it restarted.

Anyway this result didn't surprise me; I was performing such tests before. The next one was Poseidon which was keeping processor temperature at 70C for two hours. The system was stable through all this time, but I cannot guarantee that the stability was achieved due to the Pentium4 internal overheat protection. I must remind that as soon as overheating occurs, Pentium4 is starting to "omit clock cycles" that leads to significant decrease of total performance but prevents further increase of temperature. And this "critical threshold" is different for different types of processors. That is for example for processors working on 3.0GHz at Vcore = 1.525V, the performance decreases when 77-80C temperature is reached (it was figured out in the last comparison testing of Pentium4 coolers).

And finally I installed Thermalright SP-94 heatsink with Zalman ZM-F2 fan. The result has outperformed all my expectations: the processor temperature did not exceed 67 degrees.

It is natural if a reader would ask the question: is the effectiveness of SP-94 heatsink worse or better than the one of "ordinary" liquid cooling systems, which have both brass heatsink and wateerblock? One more water inexpensive (worth ~$100) cooling system took part in our testing which has shown the result of 62.5C (we will review it later in our upcoming publications). It is obvious that more expensive and systems will demonstrate better results, but the fact is: Thermalright SP-94 prolongs life of "air" cooling systems. Actually this is achieved with hard labor, that is one has to give $50-55 for a heatsink besides some $ for a good (!) fan.

Surely this review will be interesting mostly for overclockers, which choose a cooling system for the future Prescott processors. Ordinary users should not worry about anything. When these processors are issued, Intel will either overcome technical difficulties of increased heat emission or will design an effective "box" cooler.

If we make first brief conclusions, they would be the following. I can recommend only Thermalright SP-94 and Zalman 7000-Cu or -AlCu for purchasing. Concerning Poseidon system, it can be bought for not more than $30. Concerning Poseidon system, in spite of their "technological" look, their effectiveness is far from being optimal and it is difficult to recommend it for purchasing. However I haven't found prices of -T6C(Golden) in the net, and if it fits reasonable limits (say $15) these coolers will find their customer for system of "average performance".