I have now fitted the new fans. It was less of a fiddle than I expected and the result is total silence . I can feel the air movement. and I shall keep an eye on the temperature. I may not have needed to fit the voltage dropper resistors to slow the fans. Three pin fan connectors will fit to two pin...

I have acquired one of these. They're old, and the fans are noisy. The network speed they support is on the low side. They're cheap because maintenance costs money, even something simple like replacing the fans. 1: The case is held together with Torx-head machine screws, size T10. Take them out and ...