Antec Kühler H2O 920 Liquid Cooler Review

Manufacturer: Antec, Inc.
Product Name: Kühler H20 920
Price As Tested: $97.99 (Newegg)

Full Disclosure: The product sample used in this article was provided by Antec.

Since Corsair popularized their version of Asetec's "LCLC" (low cost liquid cooling) system back in 2009, it seems that every time you look, another variation on the theme appears. Other manufacturers have leafpt into the fray, and Antec's initial entry into the market, the Kühler 620, impressed us with its amazing performance. Now Antec's introduced a new product, the Kühler 920. At first glance it seems very similar to Corsair's Hydro H70 product, but Antec distinguishes their offering with exceptional performance and features.

Since all retail CPUs are boxed with perfectly good coolers (which are pretty quiet), the main reason to buy an aftermarket cooler is its performance when your processor is overclocked. (There might be some who buy coolers based on the aesthetics of their appearance through a windowed CPU case, but we'll assume they're in the minority.) But while performance is certainly the main criterion, other factors must be taken into consideration as well, such as noise, size, other features, and price. The ideal cooler keeps your processor at or near ambient temperature, is silent, free, and unfortunately doesn't exist. Manufacturers vary the performance, noise, size, features, and cost factors of their products to address different segments of the market.

Antec is best known for their line of computer cases, which have been enthusiast favorites for years. They've only recently branched out into the cooling market, and the Kühler H20 920 is their second liquid cooler.

Kühler H2O 920 Specifications

Closer Look: Antec Kühler H2O

The Antec Kühler H2O 920 box tells you everything you need to know: it's a CPU cooler, it uses liquid cooling, and it fits these sockets. This seems basic information, but you'd be amazed how often companies make you hunt for this.

The components included are the pump/radiator assembly, two 120mm PWM fans, mounting brackets, a manual, and a driver CD. Wait, a driver CD? For a CPU cooler? Yeah, we'll get to that.

The pump and radiator of the Kühler 920 appear very similar to the Corsair Hydro Series H70: it seems to use the same low-profile pump and double-thick 120mm radiator. But there are some differences.

The differences are these cables coming from the pump. From the left are the power cable, two PWM fan cables, and a USB cable. Wait, a USB cable? It's all part of the software control this cooler sports.

The Kühler mounting system is Asetek-OEM standard: a thin metal retaining ring with interior notches is secured to a back plate by four screws. The pump has notched edges; after mounting the bracket and installing the screws part-way, you insert the pump from the top and rotate it a few degrees so that the notches on the edge of the pump slide under the notches on the inside of the retaining ring. Tightening the screws will clamp the retaining ring against the pump and press it firmly against the processor. You'll actually have to assemble a bespoke bracket from the components included: four metal screw inserts must be positioned in the correct 4 (out of 12) possible places in the Intel back plate, and the retaining ring requires that 4 screws be inserted into the proper plastic offsets, which are then snapped into the retaining ring. All told, 14 different pieces comprise a complete mounting system, and paying attention and assembling the right parts correctly for your application will pay off. A slight difference here is that Antec has molded the screw holders for the Intel bracket in bright blue plastic, while the screw holders for the AMD bracket are molded in green plastic. However, the supplied manual does not call this difference out, so be careful to use the correct screw holders when assembling the bracket.

Antec Kühler Detailed Features

The Antec Kühler H2O 920's pump is the standard Asetek design: a small, flat pump with notched edges and swivel connectors for the hoses.

The Antec's hoses are soft and flexible, unlike the stiff, springy hoses used on other coolers. At about 13" long, they're also 1"-3" longer than the hoses I've seen on other coolers. The flexibility of the hoses makes installing the cooler easier, but the big news is not their flexibility, it's their size: the outside diameter of the Kühler's hoses is about 10.5mm, as compared to the 8.7mm of the hoses (measured at the narrowest point) on the H70's pump. Larger hoses can flow more water, assuming the pump can handle the extra load. Of course, in keeping with the All In One Water Cooler Technical Specifications Secrecy Act, Antec does not specify the interior diameter of the hoses.

The base of the Kühler H2O 920's pump comes with pre-applied thermal compound, but our testing regimen requires that we use the same thermal compound for all heat sinks. The base is a copper plate with a fine "satin" finish, rather than the grained finish seen on similar coolers.

The double-thickness radiator is densely finned. While the similar Corsair Hydro H70 cooler installation instructions recommend that the fans be oriented to pull outside air into the case, Antec recommends the opposite ventilation strategy, with the push-pull fans oriented to blow air outside the case.

There are no specifications (air flow or noise) for the included fans, only that they will spin at 700 to 2,400 RPM. The fans plugs into PWM leads from the pump, and their speed is controlled by electronics in the pump, mediated by the included "ChillControl V" software. While the Kühler 620 used a strange 3-pin RPM-controlled fan, the Kühler 920's fans appear to be standard 4-pin PWM devices. The combined width of the radiator with both fans installed is the same 3 7/8" as the Corsair Hydro Series H70.

Installing the Antec Kühler H2O 920 has the same slightly clumsy aspect of many water coolers: you must thread a long screw through the back of your case, through the first fan, and into a hard-to-see hole in the radiator shroud. However, the flexible rubber hoses mean that you can let the lightweight pump dangle (carefully) while you do this, and it's easy to install the pump in the loosened mounting bracket after the radiator/fan assembly is secured. The flexibility of the hoses means you can mount the radiator and pump in any orientation you wish. Once the radiator assembly and pump are secured, adding the second fan is easy. Be sure to pay attention to the direction and airflow arrows stamped into the fan frame so that it's blowing in the right direction. Once installed, the radiator and fan assembly protrudes far back into the interior of your case.

The last thing you'll do when installing the Kühler 920 is plug the USB cable from the pump into an open USB header on your motherboard, and the power cable into a fan header. Actually, considering that a single three-pin power header supplies power to the pump as well as two high-speed fans, it's probably best if you connect it directly to your power supply rather than to a motherboard fan header.

In the next section I'll discuss the installation and configuration of the ChillControl V software.

ChillControl V Software

The Antec Kühler H2O 920 is the first CPU cooler I've seen that comes with its own driver and software. Granted, the Coolit Systems Vantage A.L.C. cooler had a degree of software control built into its pump unit, but the Kühler 920 has real, Windows-installable software for controlling it. While it adds a nice degree of versatility and control, it does mean that you can't effectively use this cooler on anything except a Windows system. The software is simple and intuitive to use, for the most part, which is good since Antec includes no documentation whatsoever on it. Clicking the question mark button at the top right of the window takes you to online documentation, but at the time of this review it was "Under Construction."

The ChillControl V software has a simple interface with four primary displays: Dashboard, Graphs, Fan Control, and Settings. The Dashboard section gives an overview of the system's status, showing liquid temperature (which is not the same as CPU temperature), fan RPM and sound level, and pump RPM. At the upper right of the ChillControl window is a three-position switch with settings for "Extreme", "Silent", and "Custom" performance modes. In "Silent" mode, the fans are run at minimal RPM and the cooler is almost silent.

In "Extreme" mode, the fans run at full speed, all the time, even if the system is just idling. While this is the setting I used for testing the cooler, you'd never select it in real-world use, unless you were deaf. To say it's loud is an understatement.

Fortunately, ChillControl V has a "Fan Control" section where you can define the (liquid) temperatures at which the fans begin to ramp up from idle, and at which they will run at full speed. These settings are used when the mode switch at the upper right is set to "Custom". In this section you can also configure alerts for high liquid temperature or fan failure. While the Kühler 920 doesn't have an audible alarm, it will display pop-up alerts when these parameters are exceeded.

After experimenting with the fan control settings, I found a good compromise in setting the fans to begin to ramp up at 35 degrees Celsius and reach full speed at 40 degrees Celsius (again, these are temperatures of the coolant, not the CPU). In the image above you can see how the fan speed and coolant temperature graphs reacted to a load situation that subsequently dropped to idle.

The last part of the ChillControl V software is the Settings section. You can select how the temperature is displayed, configure logging, and most importantly control the color of the light in the "Antec" logo on the pump unit. With fine-grained control of red, blue, and green LED elements, you can set any one of 65,536 different colors! Hopefully a future software update will allow you to configure the light to pulse, strobe, and cycle through colors.

In the next section, I'll put the Kühler 920 to the test.

Heatsink Test Methodology

Benchmark Reviews is obsessed with testing CPU coolers, as our Cooling Section has demonstrated over the past few years. We've solicited suggestions from the enthusiast community, and received guidance from some of the most technical overclockers on the planet. As a result, our testing methodology has changed with every new edition of our Best CPU Cooler Performance series. Because of this, each article is really its own stand-alone product, and cannot be fairly compared to the others. Benchmark Reviews continues to test CPU coolers using the stock included fan (whenever applicable), and then replace it with a high-output fan for re-testing.

Manufacturers are not expected to enjoy this sort of comparison, since we level the playing field for all heat sinks by replacing their included fan with a common unit which is then used for every CPU cooler tested. Many manufacturers include fans with their heat sink products, but many 'stock' fans are high-RPM units that offer great airflow at the expense of obnoxiously loud noise levels, or, conversely, quiet fans that sacrifice performance for low noise. By using the same model of cooling fan throughout our heat sink tests, we can assure our results are comparable across the board. This is one of the more significant changes we have made to our test methodology, since many of the benchmark tests we have conducted in the past have compared the total package. Ultimately we're more interested in the discovering the best possible heat sink, and we believe that you'll feel the same way.

For each test, ambient room temperature levels were maintained within one degree of fluctuation, and measured at static points beside the test equipment with a digital thermometer. The Antec Kühler 920 and the comparison coolers used a common Thermal Interface Material of our choosing (listed in the support equipment section below) for consistency. The processor received the same amount of thermal paste in every test, which covered the heat spreader with a thin nearly-transparent layer. The heat sink being tested was then laid down flat onto the CPU, and compressed to the motherboard using the supplied retaining mechanism. If the mounting mechanism used only two points of force, they were tightened in alternation; standard clip-style mounting with four securing points were compressed using the cross-over method. Once installed, the system was tested for a baseline reading prior to testing.

At the start of each test, the ambient room temperature was measured to track any fluctuation throughout the testing period. AIDA64 Extreme Edition is utilized to create 100% CPU-core loads and measure each individual processor core temperature. It's important to note that software-based temperature reading reflects the thermal output as reported from the CPU to the BIOS. For this reason, it is critically important (for us) to use the exact same software and BIOS versions throughout the entire test cycle, or the results will be incomparable. All of the units compared in our results were tested on the same motherboard using the same BIOS and software, with only the CPU-cooler product changing in each test. These readings are neither absolute nor calibrated, since every BIOS is programmed differently. Nevertheless, all results are still comparable and relative to each product in our test bed (see The Accuracy Myth section below).

Since our test processor reports core temperatures as a whole number and not in fractions, all test results utilize ADIA64 to report averages (within the statistics panel), which gives us more precise readings. The ambient room temperature levels were all recorded and accurate to one-tenth of a degree Celsius at the time of data collection.

When each cooler is tested, Benchmark Reviews makes certain to keep the hardware settings identical across the test platform. This enables us to clearly compare the performance of each product under identical conditions. Benchmark Reviews reports the thermal difference; for the purposes of this article, thermal difference (not the same as thermal delta) is calculated by subtracting the ambient room temperature from the recorded CPU temperature.

Please keep in mind that that these test results are only valid within the context of this particular test: as the saying goes, your mileage may vary.

Intel Test System

• Processor: Intel Core i7-950 Bloomfield 3.06GHz LGA1366 130W Quad-Core Processor Model BX80601950, core voltage set to 1.35V
• Motherboard: ASUS Sabertooth X58 (Intel X58-Express chipset) with BIOS 0603, BCLK set to 175MHz for a processor speed of 4025MHz

Support Equipment

• AIDA64 Extreme Edition version 1.50.1200
• MG Chemicals Heat Transfer Compound 8610-60G
• Stock fan (for heat sinks without fans): Thermalright TR-FDB-12-1600 (63.7CFM advertised)
• High-speed fan: Delta AFC1212D (113CFM advertised)

All of the tests in this article have been conducted using vertical motherboard orientation, positioned upright in a traditional tower computer case. Air-cooled heat sinks are positioned so that heatpipe rods span horizontally, with the fan blowing air out the top of the chassis. The radiators of water coolers are mounted as per manufacturer instructions. In both cases, fans are connected directly to the power supply (rather than motherboard headers) and run at full speed during the test. At the start of our test period, the test system is powered on and AIDA64 system stability tests are started with Stress CPU and Stress FPU options selected. AIDA64 loads each CPU core to 100% usage, which drives the temperature to its highest point. Finally, once temperatures have sustained a plateau (no observed change in average temperatures for 5 minutes), the ending ambient room temperature and individual CPU core levels are recorded thus completing the first benchmark segment. The time to reach stable temperatures varied between 10 and 20 minutes for the heat sinks in this test; larger heat sinks typically take longer to stabilize.

The second test segment involves removing the stock cooling fan and replacing it with a high-output 120 mm Delta AFC1212D cooling fan, then running the same tests again.

Note: The Antec Kühler H2O 620, Kühler H2O 920, and the Coolit Vantage A.L.C. are designed to drive their own RPM-controlled fans directly; in the case of the Vantage, an alarm will sound continuously if there is no fan connected. For these coolers, the fans were left connected as designed during stock fan testing. For high-speed fan testing, the Delta fan was connected directly to the power supply (and the alarm on the Vantage ignored).

The Accuracy Myth

All modern processors incorporate an internal thermal diode that can be read by the motherboards' BIOS. While this diode and the motherboard are not calibrated and therefore may not display the actual true temperature, the degree of accuracy is constant. This means that if the diode reports 40°C when it's actually 43°C, then it will also report 60°C when it's truly 63°C. Since the design goal of any thermal solution is to keep the CPU core within allowable temperatures, a processor's internal diode is the most valid means of comparison between different heat sinks, or thermal compounds. The diode and motherboard may be incorrect by a small margin in relation to an actual calibrated temperature sensor, but they will be consistent in their margin of error every time.

Testing and Results

For this test, I used the following heat sinks in addition to the Thermaltake Jing:

• Thermalright Venomous X
• Cooler Master V6 GT
• Prolimatech Super Mega
• Corsair Hydro Series H50
• Corsair Hydro Series H70
• Antec Kühler H2O 620
• Coolit ECO A.L.C.
• Coolit Vantage A.L.C.
• Thermalright Silver Arrow

For heat sinks without a stock fan, I used a Thermalright TR-FDB-12-1600 fan, which puts out 63.7CFM at 28dBa according to Thermalright. This mid-range fan provides good air flow and reasonable noise levels. For "apples to apples" testing, where each heat sink is tested with the same fan, I used a Delta AFC1212D. This high-performance PWM fan is rated at 113CFM at a claimed 46.5dBa at full speed...which means that while it moves quite a bit of air, it's very loud.

The Intel Core i7-950 I used in this test runs much hotter than the Core i7-920 I'd used previously. At 1.35 volts, with a BCLK of 175Mhz, the 4,025Mhz CPU pumped out enough heat to stress the very best heat sinks. AIDA64 would report throttling once any single core reached 100 degrees Celsius; any throttling resulted in cancelling the test and recording a "FAIL". Although this overclocked and overvolted Core i7-950 represents an extreme, these are expensive, high-end heat sinks.

The chart below summarizes the results with the stock fans (hotter temperatures towards the top of the chart, and cooler temperatures towards the bottom). The twin-fan coolers (the Cooler Master V6 GT, Corsair H70, and the Kühler 920) have a real advantage here, since their dual fans move more air than the stock single fan of any of the other units. The Corsair H70's fans at their default 2,000RPM level move a lot of air together, but also generate a fair amount of noise. At the 1,600RPM level achieved with the in-line resistor cables, the noise level is much reduced, with a relatively minor performance hit.

Stock Fan Tests

And we have a new champion! With its twin fans howling away at full speed, the Kühler 920 jumps to the lead, beating the Cooler Master V6 GT by less than a degree. Following closely behind is the Thermalright Silver Arrow and Venomous X, and the Corsair H70 with its fans on high.

There's a 5.3-degree "break" between the Coolit Vantage A.L.C. and the Corsair H70, which neatly separates the coolers into "lower performance" and "higher performance" groups.

Delta High Speed Fan Tests

With the Delta high-speed fan, our lineup changes. Showing what a difference a change of fan can make, the Coolit ECO A.L.C. moves from the bottom to the chart to mid-pack, improving by almost 11 degrees. The Antec Kühler 620 improves by 7.2 degrees, putting it— amazingly— between the mighty Prolimatech Super Mega and the Thermalright Venomous X— and in fact with this fan, it beats its big brother.

The Kühler 920, though, drops far back in the pack. Although the 113CFM of the Delta high-speed fan is slightly more rated airflow than the 110CFM Antec rates the Kühler 920's stock fans at, temperatures actually rise slightly. Double-thick radiators simply don't do well with single-fan setups; you'll notice a similar performance drop with the Corsair H70 (as compared with its dual fans on high).

Liquid Cooler Final Thoughts

After Corsair's H50 hit the market, its success led to many other companies offering their own variations on the theme, if by "variations" you mean "label". Even Corsair's own H70, with its double-thickness radiator, is simply a version of Asetek's LC570 OEM cooler.

Antec's Kühler H2O systems are (so far) unique: they're not listed as OEM products by Asetek and Asetek posts no specifications on them, instead merely providing a link to Antec's product page. And as is depressingly standard in this market segment, technical information like pump flow rate are missing, so while I think the thicker hoses mean more water flow, I don't know if that's the case.

But what I do know are the performance figures I got in my testing, which place the Kühler 920 ahead of every other cooler I've tested. It solidly outperforms the similar Corsair Hydro Series H70, just as its little brother Kühler 620 outperforms the Corsair H50. Given that the radiators appear to be identical and the fans similar, the difference must lie with the pump and perhaps higher-flow tubing,

But its stellar performance comes with a commensurate cost: noise. With its twin fans running at full speed, the Kühler 920 emits a piercing shriek of sound. The ChillControl software shows the maximum sound as 56dBa, which is presumably inferred rather than actually measured. But it's still very loud, however you look at it. But remember that this is a worse-case scenario: it took the coolant several minutes to reach 40 degrees during my stress test, so unless you're running a heavily overclocked processor flat out for extended periods, you won't run into this situation. And you can ameliorate this sonic assault by using ChillControl's "Custom" setting and choosing reasonable temperatures for the fan speed ramp-up.

In previous reviews I've noted how rapidly the CPU cooler market was advancing, with new designs and new performance benchmarks appearing so frequently that it was hard to keep up. We seem to be approaching an asymptote, though: the size of air and water coolers is reaching the constraints imposed by standard computer cases, and performance is leveling off. Since any retail CPU is shipped with a perfectly good CPU cooler in the box, you might think that the only reason to purchase an aftermarket cooler is performance. While this is certainly the primary consideration, there are others, such as acoustics (how loud the cooler is) and aesthetics (for windowed cases). Also, bear in mind that not every cooler works in every situation: top-performing coolers tend to be both large and expensive, and are overkill for all but the hottest, most overclocked systems. There's room in the market for many different types of coolers, and the best solution for you is probably not the best solution for me.

The Kühler 920's performance will cost you: at an MSRP of $119.95, it's the most expensive single cooler I know of. While it is the best performing cooler I've ever tested, the Thermalright Silver Arrow and Cooler Master V6 GT come within two degrees of its performance (with stock fans) and cost $30 to $60 less, so the economic case for the Kühler H2O 920 difficult to make: it's simply not a very good value for the money. But the high end of computing hardware is filled with lust-worthy items that aren't good values, like the Intel Core i7 9xx series hexacore processors, or the NVIDIA GTX580 video cards, or even a $400 Lian Li aluminum case.

The market is full of people who are willing to pay top dollar for top performance. So if you simply must have the very best performance possible short of a bespoke water cooling system, the Antec Kühler H2O 920 is your baby.

Antec Kühler H2O Conclusion

Please remember that these test results reflect our experience with each cooler on a specific motherboard, with a specific processor, BIOS revision, BCLK and voltage settings, and test programs. The results of this test cannot be directly compared to other tests since many factors will have changed.

Installing the Kühler 920 is easier than most other compact liquid coolers due to the flexibility and length of its soft rubber hoses. The "universal" Intel backplate (on AMD systems, the stock motherboard backplate is used) keeps the parts count (and price) down, and while I prefer the more robust mounting system design of Asetek's original systems, the current mounting system certainly doesn't seem to affect the performance.

The performance of the Antec Kühler H20 920 was excellent, exceeding that of every other cooler I've tested. This level of performance does come with a rather high level of noise, although judicious use of the custom fan control settings can keep the noise in check for all but the most extreme situations.

The stock fans appear to be standard 4-pin PWM units. It's not clear if they can be replaced with other PWM fans; I suspect the cooler's software is calibrated only for the included fans. Also, higher-performance fans might draw more current than the pump's fan controller can provide.

The construction quality of the Kühler was similar to that of other Asetek-sourced water coolers, which is to say that everything fit and worked correctly and the swivel mountings for the hoses pivoted freely. Antec's adjustable-color backlit logo on the pump adds a nice bit of visual interest.

The value part of the equation is where the Kühler H2O 920 comes up short, because as of February 2012 it costs $97.99 (Newegg). Despite its amazing performance, its high price means that the Antec 920 simply isn't a very good value relative to other, less expensive coolers that perform very nearly as well. But as I discussed above, "value" isn't necessarily a determining factor in this part of the market. If you want the very best, this is it... at least until the next great cooler comes along.

Pros:

+ Best performing cooler I've ever tested
+ Integrated fan speed controller and PWM fans
+ User-controllable colored logo light
+ ChillControl software allows user to customize the performance profile
+ Maintenance-free liquid-cooling system

Cons:

- Very expensive product
- Loud at full fan speed
- Control software restricted to Windows environments only

Ratings:

• Performance: 10.0
• Appearance: 8.25
• Construction: 9.25
• Functionality: 9.25
• Value: 7.50

Final Score: 8.85 out of 10.

Quality Recognition: Benchmark Reviews Silver Tachometer Award.

Is the Antec Kühler H2O 920 on your shopping list? We invite you to comment below or start a discussion in our Forum.

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