NZXT Kraken X40 CPU Cooler Review

[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

• Prime95
• SpeedFan

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.