Heatsink Guide - AnandTech Heatsink Testing Methodology

Before publishing the upcoming Athlon heatsink comparison test, here's a short overview of the testing methodology used for the heatsink tests on AnandTech.

Each heatsink test consists of two parts: A test under real-world conditions using an actual Athlon CPU, and a test with a simulator, which is a artificial heat source that simulates the heat emission of a CPU.

The test under real-world conditions is used to judge about factors like ease of installation, motherboard compatibility, and actual overclocking results. For this test, an ASUS K7M Rev. 1.04 Athlon motherboard is being used, along with an Athlon-650 CPU. The case used is an ASUS T-10A, the power supply a Sunny Technologies CWT-300ATX (which is identical to the Antec PP-303X, which showed the best stability in the AnandTech power supply comparison). For the overclocking test, a FreeSpeed Athlon overclocking card is being used however any Athlon overclocking device will work. Temperature measurements are also made during this test, just to verify that the temperature readings obtained with the simulator really represent performance under real-life conditions.

The test with the simulator is used to judge about the heatsink's cooling performance. You might wonder why we're not using an actual CPU for the temperature measurements. Well, for one reason: Precision. When using an actual CPU as a heat source, it is hardly possible to measure exactly how much heat is emitted to the heatsink. All you could do is measure the power usage of the entire motherboard, with CPU and extension cards. In addition, the CPU power usage depends on the CPU's operating state, different combinations of instructions result in different power usage. There are simply too many variables to consider, the result is less than ideal precision.

Many heatsink manufacturers are also using heaters instead of CPUs for their internal tests, for obvious reasons.

So, the conclusion is that a suitable test device for the heatsink test was needed. This device must have the following characteristics:

•    The shape of the simulator's contact area to the heatsink must be identical to the actual CPU.

•    The heat emission of the heat source must be perfectly constant - e.g. not depend from the temperature, time, or other factors (therefore, Peltier elements are not very suitable as a heat source).

To meet these two requirements, the simulator consists of a thermal transfer plate, taken from a Athlon CPU, and two resistors as the heat source, which have a perfectly constant power usage.