Currently in the computer "220V Cooling Fan" piece bearings are mainly divided into two categories: oil shafts, ball. Both bearings will have a very good representative of the product, of course, each have their own shortcomings, it can not be denied. Oil bearing using a sliding sleeve bearing friction, lubricant use as a lubricant and DRA. Use over time, due to the oil seal, oil will gradually volatile, and dust will enter the bearings, causing the fan speed slows down, the noise increases and other issues. Many manufacturers are the basis of a number of improvements in order to achieve better results. Odor is the smell of varnish coating on the copper electric fan in operation resulting in the purchase of fans have to smell, see this paint is environmentally friendly, whether through quality testing, let you enjoy the fresh air in cool wind.