Currently in the computer "24V DC Cooling Fan" piece bearing can be 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 the sliding friction sleeve bearings, use of lubricants 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.