One and a half year ago I acquired a refurbished Optiplex 9020 tower whose power unit sadly expired two weeks ago. As I need quite a bit more power anyhow, I bought a new "Be Quiet!" PSU (with the standard 24 pin adapter) along with the "24 Pin to 8 Pin Adapter Cable" from modDIY. 

So far so good. However, after successfully connecting everything up, the PSU didn't start up, it remains as quiet as the grave I guess that some 'ready' feedback signal from the mainboard is missing. Suggestions anybody? That would be a great help because otherwise the machine would be just so much scrap iron.