Cooler Comparison Testing

Cooler Testing Methods

To best gage the quality of the system coolers under review, system CPU temperature and cooling system audio measurements were taken with the CPU idle and under load. To replicate CPU idle conditions, the system was rebooted and allowed to sit idle for 10 minutes. To replicate a stress system load, AIDA64 System Stability Test was used in conjunction with EVGA OC Scanner X for 30 minutes per run. After each run, the system was shut down and allowed to rest for 10 minutes to cool down. Then the CPU cooler was removed, cleaned, and remounted to the CPU with fresh thermal paste applied. This procedure was repeated a total of 12 times for each cooler – three times each for the stock and overclocking speed runs on the Z87 and X99-based systems.

Temperature measurements were taken directly from the CPU thermistors using RealTemp (the newer Tech|Inferno edition) for the Z87 testing and CoreTemp v1.0 RC7 for the X99 testing. Because of the volatile nature of the Haswell and Haswell-E thermistor readings, the system temperatures were measured as follows. For idle temperatures, the highest recorded value was used for the run. For load temperatures, a series of three values were notated: the average (high and low) across all cores, the average (high and low) across the single highest core, and the high temperature.

To adequately measure the Noctua NH-D9L CPU cooler performance, performance testing was done for all X99 scenarios under single fan, dual fan, and tri-fan modes using vendor provided Noctua NH-A9 fans. Single and dual-fan modes were tested on the X87 board because of fit constraints discussed previously. For testing the Noctua NH-U9S CPU cooler performance, performance testing was done for all scenarios under single fan and dual fan modes using vendor provided Noctua NH-A9 fans. Fans were directly connected to the PSU and run at full speed for all tests performed.

Note that the temperature values are reported as deltas rather than absolute temperatures with the delta value reported calculated as CPU temperature – ambient temperature. For all tests, room ambient temperature was maintained between 23-27C. Sound measurements of the system cooler where taken with the sound meter placed 3 feet away from the system with all other devices in the room silenced. The Sound Meter Pro applet on a Samsung Galaxy S3 mobile phone was used to measure decibel level.

Intel Z87-based Haswell System Testing

CPU Stock Speed Testing

The CPU stock speed testing was conducted with the BIOS defaults set for the CPU (including enabling of the CPU-integrated graphics processor) and Turbo Mode disabled, equating to a 3.4GHz CPU speed, 1600MHz memory speed, 3.4GHz ring bus speed, and 100MHz base clock. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.

Both Noctua x9x units performed well with the stock speed Haswell CPU compared with each other, but were edged out by the other coolers because of their smaller stature. The NH-9DL's dual tower design gave the unit a slight edge over the NH-U9S, mostly likely because of its center fan maintaining consistent airflow over the radiator cross-section surfaces.

CPU Overclocked Speed Testing

The CPU overclocked speed testing was conducted with known stable settings from a previous board review with Turbo Mode disabled, equating to a 4.68GHz CPU speed, 1780MHz memory speed, 4.0GHz ring bus speed, and 167MHz base clock. Also, the CPU-integrated graphics processor was disabled to reduce the processor heat generation. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.

Board voltage settings were configured as follows:

  • CPU Core Voltage – 1.25 + 0.005
  • VCCIN Voltage – 1.90
  • DRAM Voltage – 1.55
  • CPU Ring Voltage – 1.125 + 0.005
  • CPU SA Voltage Offset – +0.100
  • CPU IO Analogue Voltage Offset – +0.100
  • CPU IO Digital Voltage Offset – +0.100
  • PCH 1.05 Voltage – 1.120

Introducing the units to the overclocked Haswell processors changed both coolers' performance dynamics drastically. Neither NH-U9S in either single or dual-fan mode, nor the NH-D9L in single fan mode, was unable to complete a single test run without constant CPU speed throttling between 5-10%. The NH-D9L was dual fans was able to maintain system performance and stability, but at the knife's edge of stability.

Intel X99-based Haswell-E System Testing

Note that for the X99 Haswell-E system tests, two sets of overclocking performance numbers are reported. This was done because of disparities seen while testing air coolers in conjunction with the X99-based system. The air coolers could not keep the system stable at the same overclocked speeds that liquid-based coolers were able to maintain.

CPU Stock Speed Testing

The CPU stock speed testing was conducted with the BIOS defaults set for the CPU and Turbo Mode disabled, equating to a 3.0GHz CPU speed, 2133MHz memory speed, 3.0GHz ring bus speed, and 100MHz base clock. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.

With the Haswell-E processor, the performance characteristics of the coolers flipped with the NH-U9S taking the performance lead over the NH-D9L. The NH-U9S radiator's sheer bulk seemed more optimized to cool the larger surface of the Haswell-E in comparison to the split radiator design of the NH-D9L.

CPU Overclocked Speed Testing – Maximum air cooled speed

The CPU overclocked speed testing was conducted with known stable settings from a previous board review with Turbo Mode disabled, equating to a 4.25GHz CPU speed, 2666MHz memory speed, 3.5GHz ring bus speed, and 125MHz base clock. Also, the CPU-integrated graphics processor was disabled to reduce the processor heat generation. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.

Board voltage settings were configured as follows:

  • CPU Core Voltage – 1.275
  • DRAM Voltage – 1.23
  • All other settings set to Auto or stock settings

Surprisingly enough, only the NH-D9L in single fan mode was unable to maintain expected system speeds and stability. In all other cases, both the NH-D9L and NH-U9S performed as expected. The NH-U9S in dual-fan mode even managed to outperform the NH-D9L in tri-fan mode, but not by much.

Sound Testing

In all operating modes, both the NH-D9L and NH-U9S maintained Noctua's promise of comfortable cooling. Neither unit was audible over the normal system fan noise with the exception of the NH-D9L in tri-fan mode. The addition of the third fan increased the unit's audio characteristics noticeably.

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