Tell them to go ahead and send the tech out with the cpu fan. When the tech comes to replace it tell them what is going on and then the tech should be able to get the correct parts ordered.
One of the fans in my PSU is making an awful rattling sound.  I feel like the PSU needs to be replaced, but I cannot seem to communicate this to the tech support rep.  He keeps telling me he's going to send me a new CPU fan.  What am I supposed to do with this?  He doesn't seem to understand what a power supply is. Does anyone know how I can communicate to Dell that I need a new power supply?
XPS 8950, PSU fan rattling