Lenovo ThinkCentre A57e Hardware Maintenance Manual page 106

4. The front fan assembly is attached to the chassis by four rubber mounts.
5.
100
Hardware Maintenance Manual
Remove the front fan assembly by gently pulling it out of the chassis.
Install the new front fan assembly by aligning the rubber mounts of the front
fan assembly with the holes on the chassis and push the rubber mounts
through the holes.