[nextpage title=”Introduction”]
The Kraken X40 is a sealed liquid cooling system for CPUs, with a 140 mm radiator cooled by a 140 mm fan. Check it out!
The highlights of the Kraken X40 are the 140 mm radiator and fan (most similar products use a 120 mm radiator and fan), and a USB interface that allows you to control and monitor the temperature and the pump and fan speeds through the computer.
Figure 1 shows the box of the NZXT Kraken X40.
Figure 1: Package
Figure 2 shows the contents of the box: the radiator-block set, fans, manuals, driver and utility disk, and installation hardware.
Figure 2: Accessories
This watercooler is discussed in detail in the following pages.
[nextpage title=”The Radiator”]
The sealed radiator-block system is shown in Figure 3. At the left is the radiator; at the right is the block.
Figure 3: Sealed system
Figures 4 and 5 reveal the radiator of the NZXT Kraken X40. The radiator seems to be thinner than those that we are accustomed to seeing, but this is because it is bigger than common 120 mm radiators. It measures 5.4 x 6.8 x 1.1 inches (138.4 x 172.5 x 27.0 mm).
Figure 4: Radiator
Figure 5: Radiator
[nextpage title=”Block and Fan”]
The block, with the integrated pump, is shown in Figure 6. The manufacturer’s logo at the top is illuminated by internal LEDs, and you can choose the color of the light.
Figure 6: Block
The base of the block, which is made of copper, is revealed in Figure 7. The thermal compound comes pre-applied.
Figure 7: Base
Figure 8 shows the cables of the block. There is one three-pin connector that must be connected to the “CPU cooler” header of the motherboard, in order to power the system and tell the fan speed to the motherboard. It would be better if the system were powered directly by the power supply, especially if you plan to use two high-power fans. There is also a USB cable and two connectors for fans.
Figure 8: Block cables
Figure 9 illustrates the 140 mm PWM fan that comes with the Kraken X40.
Figure 9: Fan
[nextpage title=”Installation”]
In Figure 10, you can see the frame, backplate, and screws for use with sockets LGA1155, LGA1156, LGA1366, and LGA2011. There is a similar set of parts for use with AMD processors. Figure 11 shows the frame mounted on the block.
Figure 10: Mounting hardware for Intel CPUs
Figure 11: Frame assembled
After assembling the frame on the block, install the system inside your case. Figure 12 shows the Kraken X40 installed in our system, with the radiator at the top panel of the case.
Figure 12: Installation finished
The software that controls the Kraken X40 comes with the product. The fan (or fans, if you install a second one) can be configured for three operating modes: Extreme, Silent, or Custom, where you can program a fan power versus temperature curve. The color of the LEDs at the block can also be configured. Figure 13 shows the application screen.
Figure 13: Application screen
We tested the Kraken X40 in two modes: Silent and Extreme.
[nextpage title=”How We Tested”]
We tested the cooler with a Core i5-2500K CPU (quad-core, 3.3 GHz), which is a socket LGA1155 processor with a 95 W TDP (Thermal Design Power). In order to get higher thermal dissipation, we overclocked it to 4.0 GHz (100 MHz base clock and x40 multiplier), with 1.3 V core voltage (Vcore). This CPU was able to reach 4.8 GHz with its default core voltage, but at this setting, the processor enters thermal throttling when using mainstream coolers, reducing the clock and thus the thermal dissipation. This could interfere with the temperature readings, so we chose to maintain a moderate overclocking.
We measured noise and temperature with the CPU under full load. In order to get 100% CPU usage in all cores, we ran Prime 95 25.11 with the “In-place Large FFTs” option. (In this version, the software uses all available threads.)
We compared the tested cooler to other coolers we already tested, and to the stock cooler that comes with the Core i5-2500K CPU. Note that the results cannot be compared to measures taken on a different hardware configuration, so we retested some “old” coolers with this new methodology. This means you can find different values in older reviews than the
values you will read on the next page. Every cooler was tested with the thermal compound that comes with it.
Room temperature measurements were taken with a digital thermometer. The core temperature was read with the SpeedFan program (available from the CPU thermal sensors), using an arithmetic average of the core temperature readings.
During the tests, the panels of the computer case were closed. The front and rear case fans were spinning at minimum speed in order to simulate the “normal” cooler use on a well-ventilated case. We assume that is the common setup used by a cooling enthusiast or overclocker.
The sound pressure level (SPL) was measured with a digital noise meter, with its sensor placed near the top opening of the case. This measurement is only for comparison purposes, because a precise SPL measurement needs to be made inside an acoustically insulated room with no other noise sources, which is not the case here.
Hardware Configuration
- Processor: Core i5-2500K
- Motherboard: ASUS Maximus IV Extreme-Z
- Memory: 16 GB G.Skill Sniper (DDR3-1600/PC3-12800), configured at 1,600 MHz
- Hard disk: Seagate Barracuda XT 2 TB
- Video card: Point of View GeForce GTX 460 1 GB
- Video resolution: 1920×1080
- Video monitor: Samsung SyncMaster P2470HN
- Power supply: Seventeam ST-550P-AM
- Case: Cooler Master HAF 922
Operating System Configuration
- Windows 7 Home Premium 64 bit SP1
Software Used
Error Margin
We adopted a 2°C error margin, meaning temperature differences below 2°C are considered irrelevant.
[nextpage title=”Our Tests”]
The table below presents the results of our measurements. We repeated the same test on all coolers listed below. Each measurement was taken with the CPU at full load. In the models with a fan supporting PWM, the motherboard controlled the fan speed according to core load and temperature. On coolers with an integrated fan controller, the fan was set at the full speed.
| Cooler | Room Temp. | Noise | Speed | Core Temp. | Temp. Diff. |
| Cooler Master Hyper TX3 | 18 °C | 50 dBA | 2850 rpm | 69 ºC | 51 °C |
| Corsair A70 | 23 °C | 51 dBA | 2000 rpm | 66 ºC | 43 °C |
| Corsair H100 | 26 °C | 62 dBA | 2000 rpm | 64 ºC | 38 °C |
| EVGA Superclock | 26 °C | 57 dBA | 2550 rpm | 67 ºC | 41 °C |
| NZXT HAVIK 140 | 20 °C | 46 dBA | 1250 rpm | 65 ºC | 45 °C |
| Thermalright True Spirit 120 | 26 °C | 42 dBA | 1500 rpm | 82 °C | 56 °C |
| Zalman CNPS12X | 26 °C | 43 dBA | 1200 rpm | 71 °C | 45 °C |
| Zalman CNPS9900 Max | 20 °C | 51 dBA | 1700 rpm | 62 °C | 42 °C |
| Titan Fenrir Siberia Edition | 22 °C | 50 dBA | 2400 rpm | 65 °C | 43 °C |
| SilenX EFZ-120HA5 | 18 °C | 44 dBA | 1500 rpm | 70 °C | 52 °C |
| Noctua NH-L12 | 20 °C | 44 dBA | 1450 rpm | 70 °C | 50 °C |
| Zalman CNPS8900 Extreme | 21 °C | 53 dBA | 2550 rpm | 71 °C | 50 °C |
| Gamer Storm Assassin | 15 °C | 48 dBA | 1450 rpm | 58 °C | 43 °C |
| Deepcool Gammaxx 400 | 15 °C | 44 dBA | 1500 rpm | 60 °C | 45 °C |
| Cooler Master TPC 812 | 23 °C | 51 dBA | 2350 rpm | 66 °C | 43 °C |
| Deepcool Gammaxx 300 | 18 °C | 43 dBA | 1650 rpm | 74 °C | 56 °C |
| Intel stock cooler | 18 °C | 41 dBA | 2000 rpm | 97 °C | 79 °C |
| Xigmatek Praeton | 19 °C | 52 dBA | 2900 rpm | 83 °C | 64 °C |
| Noctua NH-U12P SE2 | 18 °C | 42 dBA | 1300 rpm | 69 °C | 51 °C |
| Deepcool Frostwin | 24 °C | 46 dBA | 1650 rpm | 78 °C | 54 °C |
| Thermaltake Frio Advanced | 13 °C | 56 dBA | 2000 rpm | 62 °C | 49 °C |
| Xigmatek Dark Knight Night Hawk Edition | 9 °C | 48 dBA | 2100 rpm | 53 °C | 44 °C |
| Thermaltake Frio Extreme | 21 °C | 53 dBA | 1750 rpm | 59 °C | 38 °C |
| Noctua NH-U9B SE2 | 12 °C | 44 dBA | 1700 rpm | 64 °C | 52 °C |
| Thermaltake WATER2.0 Pro | 15 °C | 54 dBA | 2000 rpm | 52 °C | 37 °C |
| Deepcool Fiend Shark | 18 °C | 45 dBA | 1500 rpm | 74 °C | 56 °C |
| Arctic Freezer i30 | 13 °C | 42 dBA | 1350 rpm | 63 °C | 50 °C |
| Spire TME III | 8 °C | 46 dBA | 1700 rpm | 70 °C | 62 °C |
| Thermaltake WATER2.0 Performer | 11 °C | 54 dBA | 2000 rpm | 49 °C | 38 °C |
| Arctic Alpine 11 PLUS | 11 °C | 45 dBA | 2000 rpm | 82 °C | 71 °C |
| be quiet! Dark Rock 2 | 10 °C | 41 dBA | 1300 rpm | 58 °C | 48 °C |
| Phanteks PH-TC14CS | 16 °C | 47 dBA | 1300 rpm | 58 °C | 42 °C |
| Phanteks PH-TC14PE | 16 °C | 48 dBA | 1300 rpm | 57 °C | 41 °C |
| SilverStone HE01 (Q) | 19 °C | 44 dBA | 1150 rpm | 63 °C | 44 °C |
| SilverStone HE01 (P) | 20 °C | 57 dBA | 2050 rpm | 62 °C | 42 °C |
| Thermaltake WATER2.0 Extreme (S) | 17 °C | 44 dBA | 1250 rpm | 52 °C | 35 °C |
| Thermaltake WATER2.0 Extreme (E) | 17 °C | 53 dBA | 1900 rpm | 50 °C | 33 °C |
| Deepcool Neptwin | 11 °C | 46 dBA | 1500 rpm | 56 °C | 45 °C |
| SilverStone HE02 | 19 °C | 49 dBA | 2000 rpm | 64 °C | 45 °C |
| Zalman CNPS9900DF | 23 °C | 45 dBA | 1400 rpm | 68 °C | 45 °C |
| Deepcool ICE BLADE PRO V2.0 | 22 °C | 43 dBA | 1500 rpm | 67 °C | 45 °C |
| Phanteks PH-TC90LS | 24 °C | 47 dBA | 2600 rpm | 95 °C | 71 °C |
| Rosewill AIOLOS | 20 °C | 40 dBA | 1600 rpm | 94 °C | 74 °C |
| Corsair H60 | 20 °C | 49 dBA | 2000 rpm | 64 °C | 44 °C |
| Zalman LQ310 | 27 °C | 51 dBA | 2050 rpm | 65 °C | 38 °C |
| Noctua NH-L9i | 24 °C | 44 dBA | 2500 rpm | 95 °C | 71 °C |
| NZXT Respire T40 | 20 °C | 45 dBA | 1850 rpm | 76 °C | 56 °C |
| NZXT Respire T20 | 21 °C | 45 dBA | 1900 rpm | 77 °C | 56 °C |
| Zalman LQ315 | 20 °C | 52 dBA | 1950 rpm | 57 °C | 37 °C |
| Corsair H80i (Quiet) | 19 °C | 44 dBA | 1100 rpm | 61 °C | 42 °C |
| Corsair H80i (Maximum) | 19 °C | 57 dBA | 2500 rpm | 55 °C | 36 °C |
| NZXT Kraken X40 (Silent) | 25 °C | 44 dBA | 1050 rpm | 66 °C | 41 °C |
| NZXT Kraken X40 (Extreme) | 25 °C | 53 dBA | 1650 rpm | 62 °C | 37 °C |
In the graph below, you can see how many degrees Celsius hotter the CPU core is than the air outside the case. The lower this difference, the better is the performance of the cooler.
In the graph below, you can see how many decibels of noise each cooler makes.
[nextpage title=”Main Specifications”]
The main specifications for the NZXT Kraken X40 CPU cooler include:
- Application: Sockets LGA1155, LGA1156, LGA1366, LGA2011, AM2, AM2+, AM3, AM3+, FM1, and FM2
- Radiator dimensions: 5.4 x 6.8 x 1.1 inches (138.4 x 172.5 x 27.0 mm) (W x L x H)
- Block height: 1.26 inches (32 mm)
- Fins: Aluminum
- Base: Copper
- Heat-pipes: None
- Fans: 140 mm
- Nominal fan speed: 2,000 rpm
- Fan air flow: 98.3 cfm
- Power consumption: 7.08 W
- Nominal noise level: 37 dBA
- More information: https://www.nzxt.com
- Average Price in the U.S.*: USD 100.00
* Researched at Newegg.com on the day we published this review.
[nextpage title=”Conclusions”]
The NZXT Kraken X40 proved to be an excellent liquid cooling system for CPUs. It performed wonderfully in the Extreme mode, and combined high cooling performance with low noise level in the Silent mode. The product is well-made and has an excellent overall quality.
The only issue about the Kraken X40 is about the compatibility with your case: several cases available nowadays only have openings for 120 mm fans at the rear and top panels, and the Kraken X40 needs a 140 mm fan opening. However, if your case supports 140 mm fans, the Kraken X40 will fit perfectly.
Being a great liquid cooling system, with excellent performance and flexibility, the NZXT Kraken X40 receives the Hardware Secrets Silver Award.
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