by Ilya Gavrichenkov
07/29/2005 | 05:51 PM
The manufacturers of CPU cooling solutions seem to have struck a gold vein. Becoming ever faster, modern processors have reached such a high level of heat dissipation as to require quite sophisticated cooling devices. It is now hard to imagine a cooler for latest CPU models that wouldn’t use high-conductivity materials like copper. Heat pipes and other special tricks are also employed in overclocker-friendly cooling systems, while not so long ago all-aluminum coolers could keep the processor cool. This means that making efficient CPU coolers has become an interesting and profitable business – just because the average price of the cooler has been constantly growing up.
A confirmation of this trend is that many hardware manufacturers have extended their product ranges to include cooling systems of their own design. As a result, the CPU cooler market has become more variegated with many new companies offering technologically interesting solutions.
Less traditional ways to cool the CPU have also gained more popularity recently. Particularly, liquid-cooling systems are enjoying a much higher demand nowadays because besides high efficiency they work quieter than traditional coolers, having no need for high-speed fans. Another factor contributing to the popularization of liquid cooling is that such systems have become much easier to use. PC enthusiasts once used to assemble them manually out of parts from different manufacturers, even from those who were not even associated with computers. Today, on the contrary, there are many “ready to fly” liquid-cooling systems that sometimes even include the liquid to fill the system with, i.e. they simplify the installation process as much as possible.
The number of manufacturers offering such coolers has increased, too. New names have appeared besides such renowned companies as Asetek, Innovatek and Swiftech. And for our today’s tests we’ve got a system from Corsair which is a new player in the field, too.
Yes, the name of this company is well known to each advanced user. It is the name of one of the leading manufacturers of overclocker-friendly memory modules. But now the company has added a liquid-cooling system to its product range. It’s called COOL.
Corsair’s COOL system is “ready to fly”: you won’t need anything else to cool the CPU besides what is already packed into the box. The box contains:
The components are all placed in special foam-rubber cells in the box that protect them from damage during transportation.
We want to say it right at the beginning that if you’re familiar with water-cooling kits from the leading manufacturers, you will certainly find Corsair’s COOL familiar, too. It’s all right. The fact is Corsair collaborated with Swiftech, one of the best makers of such systems, to develop its own water-cooling kit. So, COOL has many points of likeness to Swiftech’s H20-120 system which has earned a good reputation among overclockers.
Corsair also offers some additional components for COOL which are to be purchased separately. Particularly, you can buy a water-block for the mainboard’s North Bridge and a GPU water-block with all the necessary fasteners. So, no one prevents you from using COOL with other system components besides the central processor.
The COOL by Corsair kit includes two water blocks. The one with a flat bottom is universal. The other has a minor projection on its bottom for use in Socket A systems. Although the two blocks differ externally, they have identical characteristics. So we’re going to talk about the universal water block below, but everything said will be true for the Socket A block, too.
Generally speaking, the water-block largely determines the overall efficiency of a liquid-cooling system and Corsair evidently put much effort into designing one. At least, the water-block of the COOL system is very good despite its simple looks and small dimensions.
Unlike many other manufacturers, Corsair preferred a non-separable design. The block is all made of C110 copper. The black-painted shiny cap is soldered to the base. The input and output fittings are soldered to the top of the block, too. This relatively rare design of the water-block has evident advantages, however. A 100% protection against leakage is among them.
The drawbacks of the non-separable design are clear, too. You can’t see what is inside this water-block. This drawback hardly matters here, however, since we do know how the water-block of the COOL kit is designed. There are 240 copper needles on the square base of the block. The input fitting is positioned in the center and the output fitting is in one of the corners of the cap. Thus, the incoming water immediately hits the hottest spot, right above the CPU core. This circulation is considered as highly efficient.
It is important not to confuse the input and output fittings during the installation of the system. According to our tests, the wrong flow of the liquid in the water-block results in the CPU core being a couple degrees centigrade higher.
The sole of the block is flat and polished, although not to a mirror shine.
Like we said above, the water-block of the COOL kit has rather humble dimensions: it is a square with a 64mm side, and a height of 16 millimeters.
The water-block is fastened on the CPU socket with thick steel plates of varying shapes. The plates are pressed down to the mainboard with spring-loaded clips that are installed on the standard retention mechanism (Socket 478). Or you just screw the water-block down through the damping springs to the PCB (other sockets). Unfortunately, the COOL by Corsair kit doesn’t include a back plate for the reverse side of the mainboard, so you should be very careful not to deform the mainboard’s PCB.
Socket478 / LGA775
Socket 754/939 / Socket 462
You have to take the mainboard out of the system case to mount the water-block unless you’ve got a Socket 748 or Socket A system. On the other hand, you have to do it only once. If you will want replace the CPU later, you won’t need access to the reverse side of the mainboard.
The water-block comes with pipes already connected to it. The input and output pipes are about 60 cm long and are fastened to the fittings with non-detachable steel clamps. The external and internal diameters of the pipes are 1/2 and 3/8 inches (or 12.7 and 9.5mm), respectively. Funnily enough, there’s a label “food grade” on the pipes. It means these pipes are recommended for use in food engineering!
Corsair didn’t neglect such an important thing as thermal interface between the water-block and the processor: they put two small syringes with thermal paste into the box with COOL.
The pump included into the COOL kit is rather small, too. But you shouldn’t judge by the size alone – we’ve got a respectable device, Delphi pump from Laing.
The pump has a curious design. It is in fact a centrifugal pump with a rotor immersed in the liquid. Despite its small dimensions (only 6x6x4 centimeters), its characteristics are no worse than those of similar but larger devices.
Particularly, the performance of this pump is 350-400 liters per hour and it is capable of creating a water pressure of 1.5 atmospheres. This capacity should be enough to ensure proper circulation of the liquid not only through the CPU water-block and radiator, but also through a couple of additional water-blocks that can be mounted on the chipset’s North bridge and on the GPU.
An indisputable advantage of the pump employed in the COOL kit is that it requires a 12VDC power source. That is, it connects to a standard Molex connector of your power supply. It also means this pump must be situated somewhere within the system case. You can fasten it to the bottom of the case with a couple of screws or just glue it somewhere to minimize its noise. A sticky pad of porous rubber is included into the package exactly for that purpose – this material is an excellent vibrations dampener. Well, anyway, you’ll hardly have a cause to complain about the noise produced by the pump. It is no more than 24-26dB, according to the specification. According to my hearing, it is practically inaudible.
You shouldn’t worry about the extra load on your power supply. We measured the consumption of the pump and found it to be no more than 10 watts.
The reliability of this Delta pump is highest, too. Its mean time between failures is 50,000 hours which is equivalent to 5 years with something. Only high-quality components can boast such a long service time. By the way, if the pump fails, nothing too serious is going to happen to your computer because the pump is equipped with a monitoring tool. The speed of its rotor can be controlled in the same way as the system fans are controlled. To enable this, you must additionally connect the pump to a fan connector on the mainboard.
Like the pump, the radiator of the COOL by Corsair kit comes from a third-party manufacturer. It is the popular Black Ice Pro model from Hardware Labs. The Black Ice Pro is a two-pass radiator with copper ribbing specially developed for PC water-cooling systems. Having 157x133x25mm dimensions, it is intended for one 120mm fan. With the fan included (the TD1238-L-12 model from TEI) this radiator can dissipate up to 440 watts. Noise? Not more than 26dB thanks to the low speed of the fan (2000rpm). This ball-bearings fan has a MTBF of 65 thousand hours.
Unfortunately, you won’t be able to replace the fan with something more efficient easily because it has a unique power connector. This connector is attached to the plug which is located on a bracket for the back panel of the system case (this bracket is included into the kit).
As you may have guessed, the radiator is to be placed outside the system case. The pipes that lead to the radiator go through the same bracket with the fan connector. The manufacturer suggests that you hang the radiator on the rear panel of the system case. It is an acceptable place if your system case doesn’t stand right against the wall. A special system called RadBox was devised to fasten the radiator. It is a kind of steel chassis that is attached to the radiator on one side and with holes for hanging on the rear panel of the system case on the other side.
The radiator is supposed to be right against the system fan. RadBox “stands” on 1cm feet, so there is no conflict between the airflows from the system case and from the Black Ice Pro radiator.
Another advantage of RadBox is its universality. This chassis can be fastened on a system case that has places for system fans of any size (60, 80, 92 or 120mm). Thus, the owner of a COOL kit won’t have troubles finding a place for the radiator.
The external placement of the radiator of a liquid-cooling system has numerous advantages, but when the radiator is outside, everyone can see it. Corsair took care to paint the radiator black and shiny for a better visual effect:
The COOL by Corsair system uses a curiously designed expansion tank. This tank is to be installed into a standard 5.25” bay of your system case.
The tank is made of polyethylene and is shaped in such a way as to prevent air bubbles in the system. If positioned as intended by the manufacturer, the tank is the topmost point of the liquid-cooling system. This fact makes it easier to fill COOL with liquid.
The expansion tank has two fittings (input and output) and one more input fitting can be installed additionally (there’s a stopper instead of this fitting in the standard version of the kit). But if you connect additional water-blocks according to the intended scheme, i.e. into a gap in the existing circuit, you won’t need the additional fitting in the expansion tank.
There’s a hole in the top panel of the tank for adding liquid into the system. This hole is closed with a hermetic screw-top. Thus, the system is absolutely isolated from the outside world, and you shouldn’t fear any leakages even if you turn the system case upside down.
We should note, however, that the tank has no means to monitor leakages. It doesn’t warn the user if the level of the liquid in the reservoir has become lower. On the other hand, such situations are unlikely to happen in reality since the system is fully closed.
It takes some time to get this cooling kit deployed and working, but there’s nothing too difficult about the installation. Here is a list of operations you have to perform:
The kit includes everything necessary to do the installation, so you’ll just need a screwdriver and a knife to cut the pipes. The water-blocks of the COOL kit come already equipped with pipes, and the kit itself includes only one 120cm pipe. You should cut it in two to connect the pump, the expansion tank and the radiator.
The COOL by Corsair kit includes rather thick polymer transparent pipes with an external diameter of 1/2 inches (12.7mm) and an internal diameter of 3/8 inches (9.5mm). The material the pipes are made of is highest quality – it is approved for use in food machines and does not grow dim with use.
The pipe is rather flexible and can be easily put on the fittings of the system’s components. The connection is quite reliable and hermetic, so you may use the system without additionally fixing the pipes on the fittings. For reliability considerations, however, it is recommended that you fasten the pipes with the plastic clamps included in the COOL kit.
To prevent the pipe from twisting, the COOL kit includes special plastic sleeves called CoolSleeves. They look like stiff plastic springs that prevent the pipe from flattening. Well, it is in fact very hard to flatten the thick pipe of this system even without the sleeves on.
The manufacturer recommends the following connection plan: tank-pump-radiator-waterblock-tank. Additional water-blocks for the chipsets and the GPU are to be inserted into the circuit after the CPU water-block. It’s easy to fill the system with liquid – just pour it into the tank and it will quickly spread around the system which can take in about 800 milliliters of coolant.
The COOL kit comes with a 200ml bottle of special liquid for filling the system. Of course, this amount isn’t enough, so you have to add some water. Corsair’s coolant is 95% propylene glycol. By adding a small amount of this stuff into the water you prevent various organic forms of life from appearing (these microorganisms show up as green slime on the inside of the pipes). Besides that, Corsair’s coolant has some additives that give it the green color and make it shine in ultraviolet.
So after you have filled the system with liquid, you only have to put the stickers with the Corsair logo on it and check it in practice. We will do the same now, but first let us show you the official specification of this liquid-cooling system.
Specification | Corsair COOL |
Water-block | |
Dimensions (with connecting pipes) | 64mm x 64mm x 16mm |
Material | C110 Copper |
Connecting pipes diameter | ~3/8 inch internal |
CPU compatibility | Socket 462 |
Radiator | |
Dimensions | 157mm x 133mm x 25mm |
Material | Copper |
Connecting pipes diameter | ~3/8 inch internal |
Radiator fan dimensions | 120mm x 120mm x 38mm |
Radiator fan rotation speed | 2,000rpm |
Noise level | 26dBA |
Fan bearings | 2 frictionless bearings |
MTBF | 65,000 hours |
Pump | |
Pump dimensions | 62mm x 62mm x 38mm |
Pump performance | 350-400 l/h (liters/hour) |
Pump noise level | 24-26dBA |
Pump bearings | 1 ceramic bearing |
MTBF | 50,000 hours |
Expansion tank | |
Expansion tank dimensions | 154mm x 148mm x 42mm |
Expansion tank volume | 450 cubic mm |
The COOL by Corsair kit leaves a highly pleasing first impression. The system features an impressive exterior, uses components from leading manufacturers and experience of Swiftech, one of the leading makers of such cooling kits. Yet it is impossible to form a final opinion about a system without testing it in practice.
So we built a testbed around one of the hottest processors of today. It is the 3.8GHz model on the Prescott-2M core. The testbed was configured as follows:
We performed our tests at the regular frequency of the CPU and in the overclocked mode. In the latter mode the frequency of the CPU was increased to 4.3GHz (Vcore was increased to 1.4V).
Several auxiliary programs were employed for the testing. First, we used the ASUS PC Probe II utility for reading the CPU temperature data. Then, although we disabled the thermal throttling feature in the mainboard’s BIOS Setup for the time of our tests, we still checked the real frequency of the CPU with the help of the ThrottleWatch program.
To heat the CPU up we used the S&M utility which is currently the most advanced tool for that purpose. We also ran the popular Super PI benchmark to create a high, but not extreme load on the processor.
Liquid-cooling systems require special test methods. For example, it takes quite an amount of time (about 2-3 hours in the given case) for the whole volume of liquid to get warmed up. So, the temperature data below reflect the CPU temperature as it was established after the system’s working for 3 hours in the specified mode.
Since the radiator of the COOL by Corsair system is supposed to be outside the system case, we can say that it transfers heat from the CPU to the outside. Thus, the type of the testbed (open or closed) isn’t important for testing such a system. We used an open testbed, so the air coolers taken for the sake of comparison had a certain bonus.
We compared the COOL system with the results of a popular air cooler from Zalman, the CNPS7700Cu model. We also tested the reference cooler Intel supplies for its Pentium 4 670.
So, here are the results we got at the regular and overclocked frequency of the processor.
* The system would overheat and shut down with the box Intel cooler in S&M.
The advantages of the COOL system in terms of CPU cooling are evident. And, unlike many air coolers, it works almost silently. The noise from the pump and the external fan isn’t any louder than the noise from the Zalman CNPS7700Cu at 2200rpm, and this air cooler is considered among the quietest.
Efficient cooling of the CPU with liquid-cooling systems allows to reach new peaks in overclocking. As you see, we conquered 4.3GHz frequency with the COOL by Corsair kit. The processor remained stable at this clock rate even in the hardest operational modes. The box air cooler from Intel couldn’t cope with such a load, while the all-copper Zalman CNPS7700Cu evidently worked at its full capacity, close to the limit.
Unfortunately, we can’t correctly compare the efficiency of COOL with other consumer liquid-cooling systems like the recently tested 3D Galaxy from Gigabyte (for details see our article called "Out of This World" Liquid-Cooling System: Gigabyte 3D Galaxy Review). But the COOL is at least no worse than Gigabyte’s solution. The main characteristics of the systems coincide but COOL includes a more efficient copper radiator. This fact is reflected in the price of the product: Corsair’s liquid-cooling solution sells currently for about $180, while Gigabyte’s one is cheaper by half.
The release of Corsair’s COOL system marks a trend on the market of liquid cooling: high-performance and complete water-cooling solutions are becoming available and affordable for common users, not only for PC enthusiasts. The COOL system we have tested today boasts a really excellent performance. Thanks to its clever design and the use of high-quality components the system proved to be much more efficient than any air cooler. What’s important, this highest efficiency comes at a very low level of noise. Easy to install and reliable, COOL by Corsair is an excellent cooling system which can be recommended for installation in the computer of any overclocker.
Highs:
Lows: