Temps, Noise, and Conclusion

Test Setup and Methodology

Test Platform
Processor Intel Core i5-6600K
Motherboard ASUS MAXIMUS VIII GENE (mATX Intel Z170)
Memory Crucial Ballistix Sport 8 GB 2400 MHz DDR4
Graphics Card XFX AMD Radeon 5450 (Fanless)
Storage OCZ Vertex 460 120GB SSD
Cooling EK-XLC Predator 240, Corsair H100i GTX, Corsair H75DEEPCOOL Gabriel, Noctua NH-U9B SE2, Noctua NH-D14 (PWM), Scythe Ninja 4
Power Supply Corsair TX 650W PSU
OS Windows 8.1 64-bit

The test setup I employ for cooling is very simple, with all components tested under the same conditions on an open test bench. To provide accurate noise readings a passively-cooled graphics card is used, and the power supply's fan does not spin under the loads I'm using for these tests. Temperatures were recorded using RealTemp software, with the hottest core at the end of one of the identical 5-minute long tests used for these results.

As we are limited to whole numbers with monitoring software such as RealTemp, it seems safe to assume that I might have up to a +/- 1 ºC margin for error using this method. Room temperature was more precise, with a reading of ambient air (in 0.1 degree increments) taken with each CPU reading, and the final number adjusted to reflect the CPU temperature above that current room temp.

Noise was measured using a digital sound pressure meter positioned exactly 24 inches from the edge of the test system's motherboard. (Note that while great care was taken to take accurate readings, with multiple samples taken for each result, the limitation of my instrument is an accuracy of +/- 1.5 dBA.) The same meter was used for all tests with a noise floor of 33.4 dBA.

Temperature Results

With the test system's Intel Core i5 at stock speed the Ninja 4 (with fans at high speed) was very close to the performance of the Noctua NH-D14 cooler, coming out on top under maximum stress. This was an excellent showing considering the NH-D14 is one of the best performing coolers on the market, besting both the Corsair H100i GTX at its quiet setting, and the Corsair H75.

At the medium and low fan settings the Ninja 4's performance was nearly identical, and actually just a bit better on low than at the medium fan setting; though factoring in margin of error negates this. What these tests demonstrate is that the Ninja 4 is capable of performing as well at the lowest setting as it can at medium (at stock CPU speed, anyhow), so users can opt for the low fan setting (over medium) to reduce noise without impact.

Admittedly, the Core i5-6600K isn't much of a test at stock speed, so I increased the load by overclocking the processor by 400 MHz, and choosing to sync the cores to force this 4.30 GHz speed on all four threads in the next round of benchmarks.

Here the results scaled nearly identically, with the Ninja 4 actually beating the NH-D14 pretty easily to widen the gap at third place overall in this group. Here the medium and low fan speeds offered the expected difference in cooling performance as well. You might also notice that even at the lowest fan setting, the Ninja 4 was nearly 9 degrees cooler than the baseline DEEPCOOL Gabriel low-profile air cooler, which finished last.

Noise Levels

The Ninja 4 was too quiet to register above the 33.4 dBA noise floor at low or medium

Here the Ninja 4 shows is just what it was designed for. This is as silent a cooler as I have ever installed or tested, period. It literally didn't sound like it was on at the low fan setting, unless you put your ear almost on the fan. Virtually no change was audible at medium, and high was just barely louder. And the numbers you see in the chart above don't do it justice; the 33.4 dBA number is the ambient level in the room.

Without better equipment and a quieter environment (such as an anechoic chamber) I can't tell you exactly how much noise the Ninja 4 produces, but I can say you will not hear it running in your system. It was somewhere below 33.4 dBA, and to my ears inaudible from the 24-inch distance I position the sound pressure meter. Incredibly impressed here.


There isn't much left to say after seeing the noise results. It is the quietest cooler I have ever tested, and performs very well with CPU thermals. The Ninja 4 was designed to be a silent cooler and it accomplishes this with flying colors. The mounting system works well, installation was straightforward, instructions were clear. Given the performance I literally can't fault a single thing with this cooler. Outstanding!

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