Z420 Fan control solution - HP Support Community - 7015733
Amazon.com: LEYEYDOJX New Heatsink Fan 647113-001 for HP Z420 Z440 Z620 Z840 Z820 Z800,Workstation Front Case Fan Assembly 749598-001 782506-001 DC 12V 0.35A Size: 90x90x25mm 4-Wire 4-pin : Electronics
Solved: Z420 Missing memory fans and air baffles - part numbers, ple... - HP Support Community - 7522856
653905-001 HP Rear Fan for HP Z420 WorkStation
Z420 aftermarket cooler - HP Support Community - 6851510