Now I know what you're thinking because I keep hearing this around at the different forums: "Why a 60MM fan? It's only going to add noise to the unit." Well, the 60MM fan only operates when the unit is warm, and the speed is variable, so even spinning at low speeds, it's hardly audible. When the industry changed typical PSU cooling from front-to-back to bottom-and-"around the bend" a hot spot was created at the front of the PSU housing. For many PSU manufacturers, the solution was to add an acetate shiled across the back half of the fan, forcing air to move towards the back. But even this shield can add noise, and cooling over all can be affected.



Link: Johny guru