Antec Kuhler H2O 620 Review

ccokeman - 2011-03-27 19:22:57 in CPU Cooling
Category: CPU Cooling
Reviewed by: ccokeman   
Reviewed on: April 6, 2011
Price: $69.95


Getting rid of the heat generated by your CPU is one of the things we as enthusiasts constantly struggle with while we attempt to keep the CPU alive when looking for those last few MHz. Air cooling has come a long way in the past few years with solutions that vary from mild to wild. Liquid cooling, or "Water" cooling as it is known, has gathered an immense following over the past few years as parts and "kits" become available to allow the novice entry into the world of liquid cooling. First off, most people wonder out loud and question your sanity when told that you have a "water" cooling system in a computer that was just purchased for a few grand - knowing that water and electricity don't mix!. Water and electricity definitely do not play nicely together when the inevitable happens but the benefits offer a tremendous upside. That being said, there has been a proliferation of self-contained liquid cooling systems introduced over the past two years that have steadily improved in cooling performance so that they rival even some of the best air coolers out on the market. Products from CooliT and Corsair have opened the market on these efficient (and when compared to a full bore liquid cooling system) inexpensive options. Asetek, a trusted OEM supplier had partnered with Corsair on the H50 and H70 systems, the performance of which have been well documented. Asetek and Antec have teamed up to provide this addition to their Kuhler series of cooling products to bring out an easy to install self-contained system for the masses including gamers and overclockers. Just looking at the packaging and performance charts, the Kuhler H20 620 shows promise. Let's see if Antec and Asetek have teamed up for a winning combination.

Closer Look:

The full color packaging shows the Kuhler H20 620 on the front with a the socket compatibility listed along the bottom of the package. The rear shows the key components of the Kuhler H20 620 with a description of each item including the radiator/fan combo along with the tubing and pump/cooling plate combo. One side has a graph showing relative performance against both a stock Intel cooling solution and first generation LCs. The other side has the specifications for the system. The packaging has a look that will stand out on retail shelves.









The Kuhler H20 620 is housed in a form-fitted cardboard tray which guards each of the parts of the assembly in separate compartments. This method seems to work as more and more companies are using this method to house components for shipping, along with being more environmentally friendly.



The accessory package contains all that is needed to install the Kuhler 620 onto any of the supported CPU sockets. Included are a detailed instruction manual a single 120mm fan and the mounting hardware. The mounting hardware is pure Asetek OEM and comes with both an Intel and AMD backplate and socket specific spacers. Blue for Intel and Green for AMD. The main difference besides the color is the amount of holes in the spacer.



So far the Antec Kuler H20 620 looks like a hybrid design of two Asetek designs. The key is which one will it perform like?

Closer Look:

At first glance, the Antec Kuhler H20 620 looks like many of the other self-contained liquid cooling solutions out on the market. It's when you look closer that it looks like a hybrid solution. The radiator looks to be the same one used in the Asetek 550LC while the pump looks like the one used by the 570LC (the higher capacity pump assembly). One of the key differences between this product and competing products is the use of a more flexible rubber tubing that makes the installation of the Kuhler 620 less of a challenge. As you can see in the following pictures, the tubing easily forms a tight radius without kinking. The length of the tubing is long enough to use in a large chassis. The Kuhler H20 620 consists of three distinct parts, the radiator, the tubing and the pump/coldplate assembly. Each is discussed further below.














Starting off with the low profile pump/coldplate is an improved second generation design to improve cooling performance. This low profile assembly is easy to fit into tight spots where traditional high end cooling solutions would not fit while still offering excellent thermal performance. The pump assembly comes with the thermal interface material already applied in the correct amount and in the correct location. Around the edges of the pump are a series of notches and sockets. The mounting bracket hooks into these sockets to hold the pump assembly in place with the correct tension. All of the competing solutions save one, have had the cooling fan driven from a motherboard header separately from the pump. Antec's solution uses a single three pin connection to the motherboard while only having two wires being used for the pump as well as the cooling fan. This looks like all of the fan and pump control will be based on the motherboard fan setting or by voltage control. The ninety degree fitting that connect to the flexible tubing allows added flexibility when it comes time to mount this cooling solution in the chassis.




The Radiator used is designed to hold either one or two 120mm fans in "Pull", "Push" or "Push-Pull" configuration with mounting holes on both sides of the radiator. At 25mm, or one inch thick by itself, or two inches thick with a 25mm thick fan, the radiator does not take up a bunch of space in the chassis. The lightweight radiator is made from aluminum, bringing up the specter of galvanic corrosion between the copper cold plate and aluminum radiator. To combat this, Antec is using an environmentally friendly mix of demineralized water with a special glycol mix that has both anti-corrosion and antibacterial properties. This coupled with a three year warranty gives you peace of mind against leaks or a failure. Three years is about the average upgrade cycle so this cooler should last long term. The flexible rubber tubing attaches to the system with a ferrule style clamp to ensure leaks cannot occur. Though larger in the outside diameter, the rubber tubing is much more flexible than the semi-rigid corrugated tubing that was used on previous generations of self-contained LC systems.



The fan used on the Kuhler H20 620 is from Antec (as one might have guessed). The specifications are lacking in the documentation but what I do have is that it operates between 1450RPM and 2000RPM at 26 and 36dB respectively. Looking over Antec's product portfolio did not prove fruitful but a few fans had higher fan speeds and dB ratings so the scaling seems to be there as a comparison.



Installation of the Kuhler H20 620 into a chassis is a simple process. Mounting the backplate and retaining ring will require removing the motherboard from the system if your build is already complete. However, if it's a new build, no harm no foul. Set the pump assembly into the retaining ring and twist to engage the clip into the socket and tighten down the four retaining screws to complete that part of the installation. Then install the fan and radiator with the fan used in the pull configuration per Antec's instructions, tighten the four mounting screws and enjoy the benefits of a low cost (for a liquid cooling system) low maintenance cooling solution. Clearance around the socket is excellent and the solution just looks good.


Seeing Antec's approach to a liquid cooling solution shows that at least one of the major hurdles has been addressed in the tubing. The key is how will the low profile pump and slim radiator perform? Let's find out.


Fan speed
1450 - 2000 RPM
Radiator dimensions
151 mm x 120 mm (W) x 27 mm (D)
5.6" (H) x 4.7" (W) x 1.1" (D)
Noise levels
26 dB @ 1450 RPM / 36 dB @ 2000 RPM
Cooling liquid
Safe, environmentally-friendly, anti-corrosive




All information courtesy of Antec @


To gauge the performance of the Antec Kuhler 620, I will be making a comparison of the temperatures at idle and under load. Both will be made while the CPU is at the stock voltages and clock speeds, as well as when the CPU is overclocked and 'over-volted'. This will help to show what kind of cooling performance that this all-in-one liquid cooling system has to offer when compared to other socket 1366 compatible high-performance cooling solutions. These heat sinks and liquid cooled solutions will be tested head-to-head as they are delivered from the manufacturer. I could throw in a bunch of testing variables, but it is not what the products are capable of "as delivered". To test the idle temperatures, I will allow the computer to stay idle for 30 minutes and take the idle temperature at this point. For the load testing, I will use Prime95 version 26.5 and choose the blend testing and allow the processor and memory controller to heat up to the maximum temperatures. The time frame is a four-hour run, to allow the temperature to peak - usually in the 14K test. I will use Real temp 3.6 to take the high and low temperatures and average the temperatures generated over the four cores as my reported temperatures.

Testing Setup:

Comparison Heat sinks:

Comparison Heat sinks:







The Antec Kuhler H20 620 did not disappoint. It kept pace with Corsair's popular H-70 despite using only one fan and a thinner radiator. The load temperatures between the Kuhler and the H-70 were within 1 degree Celsius of each other throughout the testing. What was even more surprising with the Kuhler was that when the CPU was pushed to the 4.0 GHz mark, the Antec Kuhler H20 620 still stayed within a degree of the H-70's performance. Impressive? I'll say so. At this point the Kuhler H20 620 has bested every self-contained liquid cooling solution I have tested save the H-70. That achievement is most likely only the addition of another fan away.


Antec's partnership with Asetek has proved to be a fruitful one. At least as far as the cooling system I have tested here today goes. The Kuhler H20 620 proved to be a viable candidate for cooling down an Intel Core i7 socket 1366 based system, stock or overclocked! This thing would not stop performing even when pushing the CPU up to the 4.0GHz level with 1.375v. At 4.0GHz on the CPU, the average core temperatures were right at 71 degrees Celsius. That's all with a single fan in the "as instructed" puller fan configuration. say the least. When compared to other like systems including the Corsair H-50 and H-70, the CooliT ECO and Vantage, the Antec Kuhler H20 620 performed better than every one save the H-70 where the Kuhler H20 620 was a degree higher both in the stock and overclocked load testing. Again, it looks like Asetek and Antec have done their homework for this second generation liquid cooling solution. If that's not enough, Antec claims that the Kuhler 620 delivers load temperatures up to 20% better than the stock Intel cooling solution. A claim that is backed up in the testing both at stock and overclocked settings. I went into this review looking for performance similar to the other LCS products I have tested and was impressed with the performance first and foremost and second with the use of longer and more flexible rubber tubing in place of the rigid corrugated tubing used on other products. This added flexibility makes the installation process much easier without the fear of kinking or breaking a line. A big plus with the market this cooler is targeted at (no throwing stones, I'm in the same group). The only beef I have with the Kuhler H20 620 is that the use of dissimilar metals are used in the loop. Even though the glycol and demineralized mix has anti-corrosion and antibacterial agents in the mix, it's still a cause for concern for me. But you do get a good warranty. Priced at $69, the Kuhler H20 620 comes in at a price point that is below most of the liquid cooling solutions offered by competitors in this market segment. This makes it all the more attractive as an option to cool down a high-end overclocked rig. Sure you can get an air cooled heat sink, slap some 38mm Ultra Kaze fans on it and have a great cooling solution but then you have added cost and one thing the Antec Kuhler H20 620 does not have. A ton of noise to go along with its operation. Antec has indeed delivered a product that delivers on the promise of excellent cooling at a great price point. Add in the longer warranty at three years and this cooling solution should suffice until the next upgrade cycle.