"220V Cooling Fan" This thing speaking nothing high-tech, but to do it not only wind, noise and other performance indicators mixed, there are a world of difference on the price, a few dollars, a lot of ball fan, a few hundred pieces high-end "220V Cooling Fan" minority. Used to measure the value of the temperature-controlled fan is TOA (Temperature Over Ambient), is the difference between the ambient temperature, so you can maximize avoid environmental impacts. Noise test is based on SPL (Sound pressure level) prevail, is measured in decibels sink about 10cm, and then converted to the equivalent minus 20dB SPL decibels at a distance of 1m. "220V Cooling Fan" Performance tests are different arrangements, blue noise, red for temperature, non-overclocking results after three tables, and then there are specific tests to validate seven and nine fan blades have It is different.