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Asetek Waterchill XTernal External Water Cooling Kit
Date: Aug 29, 2006
Author: Alex Evans

Water cooling for high-end PCs is, in theory, a terrific idea. Using water to cool vital system components like your CPU and GPU allow for cooler temperatures, lower noise levels, longer component life spans and / or enhanced overclockability. Water is simply a more efficient medium for transferring heat compared to traditional metal-based, airflow cooled heatsinks. With CPU and GPU power levels increasing, it seemingly appeared as if the industry was bracing for a transition to water cooling in late 2005 / early 2006, as if the technology would be necessary in order to keep up the clock speed increases of the past year. However, a new industry wide focus on performance-per-watt has given air driven HSF coolers some new life with this latest generation of processors.

Nevertheless, water cooling is still quite attractive for two critical markets, those who like absolutely silent PC's and those who like to overclock, both of which we can say that we belong to here at HotHardware.com. Water cooling has certainly become more refined over the past several years, migrating from dangerous D-I-Y self-assembly water cooling kits to all-in-one self-contained units which do not require the user to even touch any of the water being used in the kit. The enthusiast-class kits typically require more effort to assemble, but generally provide lower temperatures and more flexibility for those who choose to take the time to learn how the technology works.

An interesting side market has emerged in water cooling, though, which looks to combine the best of both water cooling worlds into a single product line -- external water cooling kits. Quite a few companies have jumped on this bandwagon, providing an external radiator solution which sits outside of the case, cooling the water which is pumped back into the chassis to cool components. External solutions are a bit simpler to set up, as they will work with any modern chassis and don't require drilling or lots of time to set up. The general rule of thumb is that external water cooling solutions can provide better performance compared to closed circuit all-in-one water cooling devices, but can't match the performance of a true internal custom designed water cooling solution.

Today we have one of the newest external water cooling solutions on the market, the Asetek Waterchill Xternal. Certainly one of the more refined external water cooling kits to date, Asetek claims that their new solution can provide performance levels on par with internal water cooling systems with the ease-of-use of an external solution. As Asetek is one of the most respected names in the enthusiast cooling market, this lends credence to their claims. Join us as we take this excellent looking new water cooling solution for a test drive. 

Asetek WaterChill Xternal

The WaterChill Xternal cooling system is raw power in a compact solution which is easily connected to any PC using a standard rear PC card slot.

The powerful WaterChill Xternal contains the best WaterChill core components, such as:

  • Black Ice Pro 120mm Dual Radiator.
  • 4 pcs. of 120mm Low Noise Adda Fans.
  • WaterChill Xtreme [12V] pump unit.
  • 160 cm3 water reservoir with a large viewing glass.
  • 20 characters LCD module.

Capable of removing up to 200W of heat and reduce the CPU core temperature by 40-70% the Antarctica CPU cooler is the most powerful cooler on the market. The Chipset and VGA cooler effectively eliminates fan noise and increases stability.

  • WaterChill Antarctica CPU cooler CPU01/A supporting Intel S478, S775, AMD S754/S940/S939.
  • WaterChill VGA cooler VGA01/P1 supporting Nvidia GeForce and ATI Radeon cards.
  • WaterChill Chipset cooler NB01/P1 supporting Intel, AMD, SIS and VIA etc.

First ever integrated USB/Software based Control Panel including:

  • CD-Rom with Software based control unit. Easy on-the-fly configurations.
  • System and status information.
  • Temperature monitoring.
  • Adjustable and automatic fan regulation.

Detailed Information:

  • Pump speed regulation
  • Model: 03-L-7004
  • Compatibility: ATX cases
  • Materials: Aluminum Chassis
  • Tubing (OD): 10mm (3/8')
  • Power consumption: 7-12W Qmax: 1020 l/hm
  • Hmax: 240 cm
  • Width: 182mm (7.17")
  • Length: 480mm (18.90")
  • Height: 102mm (4.01")
  • Weight (non filled): 4.27 kg (9.41 lbs)
Out Of The Box


Out Of The Box

The Asetek Waterchill Xternal is composed of four individual parts, although the bulk of the system is housed in the "Xternal" unit itself, which is a combination radiator / pump / reservoir unit. In short, this means that it houses all the water in the system (reservoir), houses the mechanism which makes the water move through the tubing (pump), and houses cooling system to keep water temperature levels down (radiator + fans). The fact that all of these units are pre-assembled and self-contained in this one unit cuts down on the installation time for this water cooling system by a large factor compared to traditional water cooling systems.


Waterchill Xternal Base Unit and Waterblocks

The Xternal unit comes in black or silver, and is based around a heavy duty anodized aluminum alloy shell. The unit is sharp and looks great on top of black cases, and is roughly the size of a standard ATX tower in terms of depth. The unit is designed to sit on top of your chassis while the water cooling tubes run out of the back of the unit to the back of your chassis. It's hard to gauge the specs from images, but for those curious, the unit is 7.1" wide, 19" deep, and 4" tall, and weighs about 10 pounds without any water installed (kick it up to 12 or so with water filled). The unit is quite large in real-life, but has a great industrial look and feel to it which really showcases the quality of the product. Asetek includes rubber feet which can be applied to the bottom of the unit, allowing it to "hover" over the top of your chassis. These feet also provide an additional buffer for hot air to make its way away from the radiator.


Two (of Four) Adda 120mm Cooling Fans

Both the top and the bottom of the Xternal unit have silver fan grills (perhaps black grills would have been a better match?), which keep fingers away from the quad 120mm Adda fans which are pre-installed in the Xternal unit. These fans cool the radiator, and are both positioned to blow air downwards, meaning the top two fans bring cool air on to the radiator, while the bottom two fans move the heat away from the unit. By default, these fans run at full speed, which makes the system quite loud when first starting the system. However, using the Asetek control software, you can control fan speeds to make the unit nearly inaudible. The Adda fans are highly rated, good quality fans, although we're personally a fan of Pabst and Delta fans.

On the top of the unit, you can see a small plug which allows you to pour water directly into the Xternal from above. The unit does not use much water (only about 1/5th of a gallon), which is surprising given the size of the unit. On the side of the unit, Asetek pre-installs a see-through window which allows you to monitor water levels from the outside. This is also helpful to see if the pump is indeed active and pumping, as you can see minute variations in water flow when the unit is pumping. Great for testing purposes, and for diagnostic purposes later in the system's life, certainly. Asetek does not include any water by default (we would recommend using distilled water), but does include a syringe of Water Wetter (anti-bubble) / anti-bacterial solution with the unit.


Filling Hole and Reservoir Window

Rounding out the back of the Xternal, we see our connectors for input and output water lines, along with a 4-pin Molex style power connector and a USB port. Asetek includes an mesh-covered 4-pin power extender-style cable which runs from the back of the unit to the system's power supply, so there is no external power brick or plug to the wall needed. (Asetek claims the unit uses between 7-12 watts of power). The USB (1.1) port connects from the back of the unit to any USB port connected to the PC. This allows you to control the unit's fans, pumps, and integrated LCD screen from a Windows Interface. Let's have a closer look at this LCD, shall we?


Power Plug, USB Port, and Input/Output Hose Connectors

LCD In Action

LCD In Action

The Waterchill Xternal's "bling-factor" is most certainly its integrated LCD in the front of the unit. The LCD screen is a 20-character blue LCD with white/silver'ish characters, which interfaces to the rest of the system via the USB port on the back of the Xternal unit.


Our Name In Lights



Fan Speeds Up To 3200 RPM



Internal Water Temperature

The LCD screen provides information in regards to fan speeds, water temperatures, pump speeds, and also gives you a bit of customizability, as you can add in your own messages to be shown on the front of the screen. We could go on and on here, but pictures will provide all the information you'll need.



The Waterblocks

As mentioned before, the monolithic Xternal unit is only a piece of the puzzle for the entire kit. The Xternal unit pumps and cools the water which flows through the system, but the water must be connected to individual water blocks on heat producing components to function. Asetek bundles three separate water blocks with this kit, one for your CPU, one for your GPU, and one for your chipset.


Trio Of Waterblocks

The water block that was bundled with our kit is the Asetek Antarctica CPU01 unit, which is compatible with Socket-754/939/940 based AMD systems and Socket-478 based Intel systems. The block which we used was not compatible with Socket-775 systems by default, but includes an adapter which can be used to make the block compliant with Socket-775 systems.


CPU Waterblock

The water block is a copper based unit which has three 3.8" plug connectors on top, and is (according to Asetek) capable of handling CPU's at power levels of 200W. Top of the line Athlon64 FX-62 processors are at 125W currently, whereas top Core 2 Duo systems are at 80W, so you should have plenty of breathing room here. Water flows on to the center of the block to the sides, where it is pumped away to the next component in the water chain. Installation was a breeze on our Socket-939 test system, although the motherboard must be removed from the chassis for installation. Asetek has a terrific twist-screw tightening system which provides secure contact without letting you over tighten the unit.

After water runs through the water block, the next step in the chain is the chipset, which is cooled by the Asetek NB01/P1 chipset cooler. This copper-based unit is much smaller, but still provides more than enough cooling power for any modern chipset. The mounting system is designed for chipset coolers which are screw-based through the motherboard, whereas many modern Intel boards do not use this type of mounting mechanism. In addition, a lot of new motherboards use heatpipe-based cooling systems to cool the chipset and the motherboard VRM's, which the Asetek cooler obviously couldn't cool. This component is likely to have the most incompatibility issues, but if the unit isn't compatible with your motherboard, it can simply be left out of the cooling loop - you do not specifically need to install this component.


Chipset Waterblock

The third water block is the VGA cooler, dubbed the VGA01/P1, which is compatible with both modern nVidia and ATI graphics cards. The unit is also copper based, but features 90 degree tilted hose mounts, to save some space for other expansion cards in the system. When mounted, the GPU cooler will occupy two case slots. If you purchased another GPU water block and had an SLI/Crossfire motherboard which had two expansion slots between the PCI Express x16 slots, it could be possible to run a water-cooled multi-GPU configuration with this hardware, but Asetek does not recommend such configurations. One should also note that the VGA cooler only cools the GPU, but does not cool the hot-running DDR memory modules on modern cards. We think it would be appropriate for Asetek to provide a set of memory heatsinks, as running a modern graphics card without DDR heatsinks will un-do all the good which having a water-cooled GPU will help with. Installation of this component is relatively painless, and the hardest issue will likely be removing the stock cooler from your graphics card.


GPU Waterblock

Since all of these components use standard 3/8" water tubing, it's also possible to purchase additional water blocks which this kit doesn't include by default. For example, Asetek sells a water-based hard drive cooling system which could hook up to this set up quite easily. However, the more components you add to the water cooling system, the less effective it becomes, as flow rates drop and more components are adding heat to the water, the fans have to work harder to get rid of this extra heat.

Once all the waterblocks are installed on their varying components, one simply has to connect the correct tubing between the Xternal unit and all of the blocks. Asetek includes a three meter hose which has to be manually cut to fit the lengths of your individual system. If you've never worked with a water cooling kit before, this can be scary, but the whole process is really quite simple. Measuring, cutting, and connecting the cables took about ten minutes altogether. Asetek uses high-quality connectors, so once the hose is connected, it's quite difficult to remove unless you're directly pulling on the tube. When moving around the blocks, the hoses won't come loose or leak. We would, however, have liked to see some quick release connectors on the back of the Xternal unit, to allow you to move the unit if need be (i.e, the Zalman Reserator Series 2 units have these). While the system is flexible, once you get it up and running, you're not going to want to make any major modifications to it.

Testing and Setup

Testing and Setup

We assembled a test system outside of a chassis to ensure the system would be fully functional and would not leak. It's a good practice to do, if you have the time and effort to spend on water cooling system setup. Ideally, you test the water loop and blocks for any leaks by running it for several hours or a day, and once you're satisfied you re-install the kit in your chassis. With the Asetek kit, this can be somewhat difficult, as there are no quick drain plugs or quick release connectors - so if you want to move the system from outside of a chassis to inside, you have to pull plugs and drain all the water and start over from scratch. Not exactly a fun process.


CPU Waterblock Installed On Opteron 170 Processor

Starting up the kit for the first time was not a very good experience. Without the Windows based software to control fan speeds, the unit kicks all four 120 mm fans on at full speed, making the system quite loud until you get your operating system set up and the Asetek software installed. That we can deal with. Unfortunately though, our Waterchill Xternal unit leaked quite a bit upon originally starting up the system. The leakage was not in any of our newly created water loop, but with the Xternal base unit itself. After about a minute of the unit being active, we noticed a fairly large pool of water dripping from the bottom of the Xternal unit, directly through the exhaust fan cutout holes. Obviously, leaks are bad, but when leaks are happening right next to powered components, we're looking at a dangerous scenario.

We cleaned up the excess water and continued to run the system while keeping a close eye. After around ten minutes, the system stopped leaking and has not leaked a drop in the week or so we've been testing the unit. It looks like a seal wasn't as tight as expected. This certainly is not a good sign, but I've seen water cooling kits do far stranger things, so it's not a huge deal in this case. Anytime you deal with water cooling, you will get wet somewhere, somehow. Just be prepared with a dry rag and you'll be fine.


GPU Waterblock Installed On GeForce 7800 GTX Graphics Card

As mentioned before, the four fans running at full blast can be quite loud. These fans can run at 3,200 RPM at maximum speed, but they can be tuned using the Asetek software to use down to 20% of their power, cutting down RPM levels to 1,500 RPM (although, this number should be lower). At power levels under 20%, the fans would not spin. You also have the ability to turn off "sets" of fans. For example, you can leave the top set of fans going but turn the bottom set off.

While you can run the system without any fans, your temperatures will rise rather quickly. We found that by running a single set (2 fans) at 40% provided the best mix of low-noise and cooling power. With only two 120mm fans running at around 1500 RPM, our noise levels were very low, but the system was fully happy running our overclocked Opteron 170 processor and overclocked GeForce 7800 GTX graphics cards, and was able to do so at lower temperature levels compared to air coolers which are much louder.

Performance Numbers


Performance Numbers

Test System Specifications
Water Cooled and Ready To Roll
  • AMD Opteron 170 (2.0 GHz) Socket-939 Dual-Core Processor
  • MSI K9A Platinum, ATI Radeon XPress 3200 Crossfire Chipset
  • 2 GB Samsung DDR-400 Memory
  • 1 x nVidia GeForce 7800 GTX 256 MB (91.31 Forceware Driver)
  • 2 x Western Digital Raptor 74 GB
  • 1 x Sony DVD+/-RW Drive
  • 1 x Antec 550W Power Supply



Our first set of tests were with a closed loop (CPU only) configuration testing the Waterchill Xternal versus other air-cooled units on our stock clocked Opteron 170 processor at varying fan speed levels. The numbers show very little difference in CPU temperatures when the system is idling, however, the Waterchill Xternal is much more effective compared to air coolers when CPU load levels are high. Even passively, the Waterchill was able to provide temperatures on par with the Zalman CNPS9500, one of the top air coolers on the market today.



Our GeForce 7800 GTX GPU actually ran slightly warmer compared to stock air coolers when idle, likely as the GPU receives warm water after it's passed from the CPU and chipset previously. However, when the GPU is stressed to the breaking point, the Xternal can provide better temperatures compared to air-cooled methods. The big point here is that the Xternal is far, far less annoying when it comes to noise levels compared to most GPU coolers on the market.


Asetek's Waterchill Xternal has the same core feature set as their previously released Waterchill unit, which itself was well received by the enthusiast community. The Xternal variant simply takes these technologies and packages them up in a sleek aluminum alloy chassis, simplifying installation and allowing the product to be considered by a larger amount of potential buyers worldwide. It's not exactly an innovative concept, as several other companies have treaded these waters (no pun intended) as well. However, of the external water cooling kits we've seen, Asetek's Waterchill Xternal certainly is the sleekest and most professional implementation to date.

The Waterchill Xternal is by far the most attractive water cooling external unit we've seen yet, using anodized aluminum alloy with an integrated (customizable) LCD screen on top. The entire package is thought out very well, from the integrated reservoir window to the rubber feet to minimize vibrations. We're very much in favor of the vast majority of the features which Asetek has implemented, however, we would love to see quick release connectors in future revisions, as this would allow the unit to be moved separately from the chassis if need be. This would also greatly help moving the unit from one system to another, which is a painful process with the Xternal unit at this time.

The waterblocks are all very high quality and were fairly easy to install. We didn't encounter any leakage issues with the stock waterblocks, as all of the units and tubing were very high quality and a snap to install. While we found the installation to be quite simple, we've worked with water cooling gear before and know how the basic flow patterns are supposed to work. Asetek's bundled manuals are surprisingly small and not very thorough, as they are clearly designed for someone with knowledge of water cooling. Beginners, however, may have some trouble with installation. We were able to get our Asetek Waterchill Xternal Kit together in about two hours from start to finish.

We unfortunately had an issue where our unit was leaking internally during early testing. The leak stopped once a seal properly seated, but this could have turned into a major issue had the internal circuitry shorted and lead to an early unit death or possibly even worse. This issue kept the Waterchill Xternal from getting solid high-scores across the board. Beyond our leakage issue, the Xternal unit performed great, providing low temperatures and low noise levels, and also allowed us some extra overclocking headroom. It's an expensive unit at $350, but provides better performance than $150 or so of high-quality air-cooled heatsinks would provide, and also allows for lower noise levels. It's a tough call as to whether or not the extra investment is worth it, but Asetek does offer a compelling product here. 


  • Great Looking, High Quality External Unit
  • Low Temperatures, Enhanced Overclocking
  • Low Noise Levels, User Controlled Fans Speeds
  • Integrated Customizable LCD Screen
  • Leaking Base Unit
  • Lackluster Installation Instructions
  • Costly In Comparison To Air-Cooled Hardware


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