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[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.

NZXT Kraken X40Figure 1: Package

Figure 2 shows the contents of the box: the radiator-block set, fans, manuals, driver and utility disk, and installation hardware.

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 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).

NZXT Kraken X40Figure 4: Radiator

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 6: Block

The base of the block, which is made of copper, is revealed in Figure 7. The thermal compound comes pre-applied.

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 8: Block cables

Figure 9 illustrates the 140 mm PWM fan that comes with the Kraken X40.

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 10: Mounting hardware for Intel CPUs

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 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.

NZXT Kraken X40Figure 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

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.

NZXT Kraken X40

In the graph below, you can see how many decibels of noise each cooler makes.

NZXT Kraken X40

[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.