Thermalright HR-02 Passive Processor Heatsink Review

Looking to cool a 130 watt processor with a passive heatsink? I am not sure many of us are, but if you are looking to silence a powerhouse enthusiast system, passive cooling is now a way you can go. We have a look at Thermalright's passive HR-02. And yes, you can put a "silent" fan on it as well if you wish.


I quite literally cannot remember the last time a company produced a heat sink intended for use without a fan. (Editor's note: I have actually been using a Dynatron G950 passive heatsink on a Core i7 980X for over a month now so there are other companies doing this. But you will find horror stories on the Dynatron's fit and finish, so it nowhere comes near to carrying Thermalright's torch when it comes to attention to detail and quality.) Oddly enough, as CPUs have increased in performance and cores the power envelopes have stayed the same maxing out at around 125 watts to 140 watts without overclocking. One would think with advances in heat sink design we would see more passive coolers able to sustain a CPU but this just isn’t the case. Perhaps it’s because the manufacturers feel there is no money to be made offering a product that isn’t Extreme, offers Turbo Mode or some other over used superlative. Maybe it’s because other manufacturers lack imagination.

Well it seems there is one company with some imagination left and it doesn’t come from a tiny, radical thinking start-up. It comes from one of the most well known, established heat sink producers in the world, Thermalright. The review's title took my thunder, I know. Thermalright is looking to join the leagues of silent PC enthusiast that are not neccessarily looking for a "low power" processor. Enter the Thermalright HR-02.

Article Image

System Setup

All testing of the coolers will occur, one again, inside our NZXT Tempest Evo case. This is per Thermalright’s installation recommendations and to create airflow similar to what you would see at home. Given this is a passive cooler, testing it on an open bench really does not tell us anything since we would not be creating an airflow dynamic around it. Our system will have installed a GIGABYTE X58-Extreme motherboard, six gigabytes of Corsair DDR3 RAM, with the Intel Core i7 920. With four cores and triple channel memory populated expect to see lots of heat. The video card of choice is the NVIDIA 9500 GT thanks to its low heat output and silent fan.

Article Image

Article Image

Test Methods


In keeping with the spirit of the [H] we are once again doing hardware testing of all heat sinks. This means milling a very small path into an expensive CPU to place our thermocouple into. This is by far the best way to test coolers and the only way here at the HardOCP.

Article Image Article Image Article Image

Temperatures for the CPU will continue to be measured using our Sperry Digital 4 Point thermometer.


For this article the GPU will be kept at stock speed to keep any excess heat away from the CPU that could impact the results. In 2D mode the 9500 GT generates very little heat and to further isolate it from the rest of the system we will install it in the secondary PCIE slot.

Thermal Paste

Noctua's NT-H1 thermal paste was selected as the paste of choice for a few key reasons. The thermal paste has been shown to provide excellent thermal conductivity allowing the heat sinks to better do their job. There is no observed curing time. That is, performance does not get any better over time. Any curing time could have introduced variables into the equation causing at best dubious results and at worst unreliable ones. Our channel milled CPU also requires a compound that is more viscous so the mating compound will not seep into the channel and run off.


Ambient temperature will be kept at 25C for the duration of the tests and measured with a MicroTemp EXP non-contact infrared thermometer and cross referenced with the Sperry Digital 4 Point thermometer. Any variance greater then 0.2C will halt the testing until temperatures return within spec for fifteen minutes.


Idle temperatures will be recorded after a fifteen minute period of inactivity. Any fluctuation during the last sixty seconds will reset the timer for an additional five minutes.


Load temperatures will be recorded after a fifteen minute period of 100% load. To obtain this load we will be using Prime95 v25.3 set to blend mode. In this way we can heat up the CPU as well as the memory controller which is now integrated into the die. Any fluctuation during the last sixty seconds will reset the timer for an additional five minutes.


Sound levels will be measured with a Reliability Direct AR824 sound meter from a distance of four feet away. With everything turned off and the room completely silent the meter registered a sound level of 38dB(A). This is a very quiet room where a simple pin drop could be heard. All sound measurements are recorded in the very late evening to further reduce any ambient noise.