These were a perfect replacement for the extremely loud 40mm fans in my Dell PowerConnect 5548 switch. I had to repin them to the Dell proprietary pin layout, but after completing that there was a noticeable decrease in noise. A word of caution, the 40mm fans require specific 40mm fan screws and cannot use generic case fan screws. I attempted to use the generic ones and ended up cracking the screw mount on the fan.