Corsair H70 Water Cooler Performance Testing

Last time around with the Corsair H70 we compared it to its elder H50. This time we stock the field of comparison with a couple more heavy hitters from both the water cooling and air cooling categories while conducting all tests in-chassis, just like you would see in a real world build.


In our original review of the Corsair H70 we found the cooler to perform very well for a fully sealed kit as well as for the price. We compared it to its predecessor, the H50, as well as the stock Intel box cooler for reference. Today we pit the unit against some higher end contenders as see if the H70 can hold its own.

Testing these sorts of closed loop coolers present some challenges when conducting performance testing. It is impossible to get comparable results using our traditional bench testing methods. Today's tests were all conducted inside a traditional ATX computer chassis.

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System Setup

Today's testing will occur a little bit differently than usual as is mentioned above. The test bed still consists of the GIGABYTE X58-Extreme motherboard, six gigabytes of Corsair DDR3 RAM and the Intel Core i7 920. But today we are putting the systems inside the NZXT Tempest EVO case. The reason is because open bench testing is not going to give us a good basis of comparison like we can get on air coolers. All units will be tested inside the closed chassis to give us some "real world" data. Of course, still everyone's chassis and airflow in it is going to be a bit different, so you mileage may vary.

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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.

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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.

Since we are dealing with water cooling we will allow extra time for each test to give the water in the loop enough time to reach equilibrium.


Idle temperatures will be recorded after a twenty-five 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 twenty-five 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.