How we test
With our Socket 1155 and Socket 2011 Ivy Bridge CPU simulator we test CPU coolers with a various amounts of heat: 65 W, 95 W and 125 W. These are professional CPU simulators that replicate the exact heat production and signature of a Socket 1155 Ivy Bridge and Socket 2011 Sandy Bridge-E processors. They also fit into the official processor sockets and produce heat the same way a real CPU does. That means that the Socket 1155 has separate heat generators for the CPU and GPU parts. The temperature sensor is now integrated into the CPU simulator. The temperatures that we record are therefore representative of the heat produced by real processors.
65 W and 95 W are the TDP values of the majority of Socket 1155 processors. 125 W equals about what a reasonably overclocked processor will produce. With the Socket 2011 Sandy Bridge-E CPU simulator we test at 130 W and 160 W. The first is the TDP of the actual Socket 2011 processors, and the second corresponds to an overclocked version.
We perform each measurement twice, once with the CPU cooler fan running at full speed (12V) and once with the fan running on low speed (7V). We normalize the results to an ambient temperature of 20 degrees Celsius.
We also measure how much noise a CPU cooler creates. We do this in a sound-proof box at a 10 cm distance from the source, again once with the fans running at high speed (12V) and at low speed (7). We use a professional Brüel&Kjaer 2238 sound level meter.
To make the relation between temperature and noise production more understandable, we create a chart for efficiency as well, by multiplying temperature by noise production. The lower the result, the better. We calculate these values at 100 watts. The most efficient cooler combines effective cooling with low noise levels. These efficiency numbers aren't exactly scientifically-sound, but do provide a useful reference point for comparing CPU coolers.
The Hardware.Info CPU cooler test