9020 is proprietary 8 pin power supply. Requires 24 to 8 pin adapter. There is even a guy who designed his own adapter [URL] [URL] Recommended Replacement is EVGA 700BR [URL] [URL]      
I need help, my Dell Optiplex 9020 (MT) wouldn't turn on, There's no light on the power button, white, amber or blue,... I tried performing the Power Supply self-test using the BIST button on the back, The Power Button LED does not turn on, both ODD drives LED on my PC turns on, CPU/GPU fan on, case fan on. I tried unplugging my external components and internal, still the same issue, could it be the power cord to the PSU causing the problem ?!? Please help ;-; .
Dell Optiplex 9020 (MT) Power Issue???