Date:
Tuesday , July 08, 2008
Author:
Marc Adams
Editor:
Kyle Bennett
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Kingwin Heat-pipe Direct Touch CPU Cooler

Heatpipes have been all the rage for years now. And lapping your mating surface has been all the rage for the last decade. What happens when you take a round heatpipe and make it your actual mating surface? Kingwin answers that question for us.

Introduction

Today we are going to look at a new take on a well established technology; the heat pipe. For year, manufacturers have been including heat pipes in their designs as their ability to transfer heat just can’t be matched without exotic (expensive) materials. Of course the way they have been used varies greatly from one design to the next. Then somewhere along the line the designers got the idea the remove the middle man from the equation. The middle man being the contact plate that encases the heat pipes and makes contact with the CPU. The idea is to have the heat pipes ground flat on the bottom so it makes direct contact with the CPU facilitating the transfer of heat; hopefully resulting in better cooling. Sounds practical enough. Kingwin is here today with three of their very best coolers utilizing this technology they’ve dubbed “H.D.T.” or “Heat-pipe Direct Touch.” We have on hand the RVT-9225 which is your standard tower design with a 92mm fan, the RVT-12025 which uses the same design but is larger with a 120mm fan and the RVT-12025D which is a downward facing design also using the larger 120mm fan. Lackluster names aside, we intend to find out if Kingwin’s H.D.T. coolers have what it takes to de-throne the reigning King of Cooling or will it, like all others, bow down to mighty performance of the Thermalright Ultra-120 Extreme.

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System Setup

All testing of the ASUS coolers will occur on our standard test bed. This consists of the Asus Maximus Formula paired with none other than the Intel QX9650. You guys asked for quad-core testing and you got it. The video card of choice is the NVIDIA 7900GTX thanks to its dual slot cooling solution and low heat output.

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Test Methods

CPU

When we concluded the first roundup of CPU heat sinks Kyle and I both came to the same conclusion. Software monitoring just isn't going to cut it. We need to step it up the [H]ard way. That is just what we did. We reached out to Intel about using a hardware monitor drilled into the IHS to measure the CPU temperature and wouldn't you know it, this is the exact way Intel tests their own chips. Now we knew we were on the right path. A few weeks later and a little planning along with some specifications and we were able to do it just like Intel does.

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Temperatures for the CPU will be measured using a Sperry Digital 4 Point thermometer. We can also monitor the temperature of the North Bridge through the Asus Probe application. This will let us know if the heat sink provides any additional cooling to other components. Something that becomes more and more important as you overclock.

Now you may be asking why we didn’t just use a quad core CPU and continue monitoring temperatures through software. Take a look at this table. These measurements were recorded using the Intel stock cooler with the CPU at default settings. Core-Temp reports the individual temperature from each core.

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With large discrepancies and variations between programs, this is why we chose hardware monitoring.

GPU

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 7900GTX under clocks its core to 275MHz which creates very little heat and allows the fan to run at inaudible levels.

Thermal Paste

Noctua's NT-H1 thermal paste was selected as the paste of choice for a few key reasons. Firstly, the thermal paste has been shown to provide excellent thermal conductivity allowing the heat sinks to better do their job. Secondly, 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. Lastly, because we have a special CPU on our hands it requires a compound that is more viscous so not to seep into the channel and run off.

Temperatures

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.

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Idle

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

Load temperatures will be recorded after a fifteen minute period of 100% load. To obtain this we will be using Prime95 v25.3. We have previously used Intel's Thermal Analysis Tool (TAT) to create a load on the CPU but this application is not designed for quad-core CPUs. Any fluctuation during the last sixty seconds will reset the timer for an additional five minutes.

Sound

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.