Just a couple of months ago I assembled a PC and to cool the graphic card, i mounted a 2" fan on the side of the box using plastic wire fasteners.
That caused vibration coupling and the PC runs with a low audible whine due to the vibrating fan attached to the side of the PC. This gets irritating in no time.
After reading various SPCR articles and researching the web, I tried an interesting rubber band mounting by stringing rubber bands through the mounting holes on the fan to the box.
Vibration isolation is very much achieved and noise becomes pretty much lower that I could literally sleep in the bedroom with the PC on
Before this using plastic mounting straps:
After using rubber band mounting:
Low frequency vibration is well reduced.
Note that measurements are not very accurate but illustrates the point.