Has anyone else gone through this dilemma ? Any help would be much appreciated (fan header pinout, Service Manul or schematics for Delta DPS-1050DB A, etc.).
Yes, my original chassi fans in my Z800 sounded like a Cessna airplane but when i changed them to Noctua fans i got an error from the BIOS each time i booted the computer. I gave up and bought new chassi fans for the Z820 since they are much quiter than the fans in the Z800. (I assume that Z840 fans are even better today.)
Front chassi fans were no problem to get but the rear double-fan with it´s sepcial fan connector was harder, but i managed to get it. The two 80mm fans in the power supply sounds like a Cessna plane as well, so be preprared...
Not the answer you were looking for, but can be good if you one day decide to give up. 