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NZXT Kraken X73 & Z63 AIO CPU Cooler Review

To measure the performance of CPU coolers, we devised an easily repeatable series of tests. The only variable is the coolers themselves to ensure the results can be accurately compared against one another.

Test Rig

  • CPU – Intel Core i9-9900K
  • Motherboard – Gigabyte Z390 Aorus Master
  • Memory – 16GB (2x 8GB modules) Patriot Viper RGB 3600MHz CL16
  • Storage – Corsair Force LE120 120GB SATA SSD
  • Power supply – Seasonic Prime PX-850m 850W 80+ Platinum
  • Thermal compound – Corsair TM30
  • Chassis – Open test bench
  • Operating System – Windows 10 1903


Thermal Testing Procedure

The procedure will consist of several tests that will produce six temperature readings for each cooler. The data can then be used to compare thermal dissipation performance.

First, we will lock the Intel Core i9-9900K at its 3.6GHz all-core base clock speed, with a 1.15V Vcore applied in the BIOS. Then, let the system idle in windows for 15 minutes and measure the average temperature over this 15 minute period. At the same frequency, we will then measure the load temperature over a 15 minute period.

To simulate overclocked frequency, we will then lock the Core i9-9900K to 4.7GHz on all cores with a 1.20V Vcore and run the same idle and load test again. To measure an extreme overclocking situation, we will lock the Core i9-9900K frequency to 4.9GHz on all cores with 1.30V Vcore and run the tests one final time – this should push the limits of the cooling performance of even the very best CPU coolers.

Admittedly, the overclocked frequencies/voltage may not be the highest achievable, nevertheless, it will give us a good set of data to compare the effect frequency/voltage changes have on temperature.

The temperatures presented in the graphs will be average Delta temperatures measured over the length of the test. We will calculate the Delta temperature by deducting the ambient temperature in the test room from the measured CPU temperature, both at idle and under load.

All idle temperatures are measured by letting the system idle in Windows for 15 minutes. Load temperatures are achieved by running AIDA64 stressing CPU, FPU and cache again for 15 minutes. This should give the CPU enough time to reach its maximum temperature. Throughout testing, Load Line Calibration will be set to level 6 (turbo) in BIOS and all CPU Fans/pumps set to maximum RPM to find the raw thermal performance of each cooler. During the 15 minute idle and load periods, CPU temperature is logged by HWINFO and an average CPU temperature is calculated from this data.

To measure the thermal performance of each CPU cooler with noise normalised, we will run the 4.7GHz load test one final time with the noise output of the CPU cooler at 40dBA, which is measured using a sound meter placed 1 meter from the test bench. Noise normalised testing will determine the efficiency of the cooler at a given noise level.

Noise Testing

Maximum noise levels will be measured with our sound meter at a distance of 1 meter from the test bench. The cooler’s fans/pump will be set to their maximum RPM rating. The ambient noise level in the room is measured at 37.3dBA, the peak noise level of the cooler will be recorded in dBA.

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