Testing Methodology

Manufacturers are not expected to enjoy this sort of comparison, since we level the playing field by replacing their included fan (whenever applicable) with a common unit which we then use for every CPU cooler we test. Manufacturers regularly include fans with their CPU cooler products, and more often than not these fans are very high RPM units which offer great airflow at the expense of an obnoxiously loud noise level. By using the same model of cooling fan throughout our testing, we can assure our results are comparable across the board. This is one of the more significant changes we have made to our test methodology, since many of the benchmark tests we have conducted in the past have compared the total package. Ultimately we're more interested in the discovering the best CPU cooler performance and we believe that you'll feel the same way.

Testing was conducted in a loosely scientific manner. Ambient room temperatures levels were held to within one degree of fluctuation measured at static point beside the test equipment with a calibrated digital thermometer. All coolers had their original manufacturer-supplied fan removed and replaced with our common test fan listed in the support equipment section below. Each product then received the same amount of Thermal Interface Material (specified below), which amounted to roughly a BB-sized drop placed onto the center of the CPU. The CPU cooler product being tested was then laid down flat onto the CPU, and compressed to the motherboard using the supplied retaining mechanism. If the mounting mechanism used only two point of force, they were tightened in alternation; standard clip-style mounting with four securing points were compressed using the cross-over method. Once installed, the system was tested for a baseline reading prior to testing.

At the start of each test, the ambient room temperature was measured to track any fluctuation throughout the testing period. EVEREST Ultimate Engineer Version 4.60 was then utilized to create core loads and measure each individual CPU core temperature. It's important to note that software-based temperature readings reflect the thermistor output as recorded by the BIOS. For this reason, it is critically important to use the exact same software and BIOS versions throughout the entire test cycle, or the results will be incomparable. All of the units compared in our results were tested on the same motherboard using the same BIOS and software, with only the product itself changing in each test. These readings are neither absolute nor calibrated, since every BIOS is programmed differently. Nevertheless, all results are still comparable and relative to each products in our test bed.

One unfortunate problem is that CPU's report temperatures as a whole number and not in fractions. This in turn causes the motherboard BIOS and subsequent software applications such as EVEREST to also report to the nearest whole number. To compensate for this, our tests were conducted several times after complete power down thermal cycles. Conversely, the ambient room temperature levels were all recorded and accurate to one-tenth of a degree Celsius.

When I tested each cooler, I made certain to keep the hardware settings identical across the test platform. This would enable me to clearly compare the performance of each product under identical conditions. While the ambient room temperature did fluctuate between 20~22°C, this would not be enough to cause a noticeable impact on our test results since only the thermal difference is reflected in the charts. For the purpose of this article, thermal difference (not the same as thermal delta) is calculated by subtracting the ambient room temperature from the recorded CPU temperature.

Test System

• Motherboard: Gigabyte GA-EP45T-EXTREME (Intel P45 Chipset) with version F4 BIOS
• Processor: Intel E8400 Core 2 Duo 3.0 GHz overclocked to 3.6 GHz
• System Memory: Super Talent PC3-14400 DDR3 1800MHz W1800UX2GP
• Disk Drive 1: OCZ SATA-II 32GB 2.5-Inch SSD OCZSSD2-1S32G
• Optical Drive: ASUS BC-1205PT SATA Blu-ray Disc Optical Drive
• Enclosure: Cooler Master Cosmos RC-1000 Mid-Tower ATX Case
• PSU: ePower Technology EP-1200P10 xScale 1200W PSU
• Grpahics: ZOTAC GeForce 9800 GTX+ Zone Edition (liquid cooling tied to P45 Northbridge)
• Monitor: Honeywell 22-Inch LCD Monitor MT-SY-HWLM2216
• Operating System: Windows XP Professional SP-3 (optimized to 16 processes at idle)

Support Equipment

• OCZ Freeze Thermal Interface Material (No curing time necessary or given)
• Yate Loon 120mm cooling fan, model D12SH-12 (88 CFM @ 40 dbA)

All of our tests are now conducted using only the vertical motherboard orientations traditional to tower computer systems. At the start of our test period, the test system is powered on and EVEREST system stability tests are started with Stress CPU and Stress FPU options selected. Then for a minimum of thirty minutes EVEREST loads each CPU core to 100% usage, which drives the temperature to its highest point. Finally, once temperatures have sustained a plateau, the ending ambient room temperature and CPU core levels are recorded and the first benchmark segment is complete.

The second test segment involves removing the stock cooling fan and replacing it with a high-output 120 mm Yate Loon D12SH-12 cooling fan. The system is given thirty additional minutes with EVEREST loading the CPU cores before final temperature readings are taken and recorded.

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