3020 7020 9020 xe2 inspiron 3250 1 if dell mt standard size atx psu 24 pin will work using 24 pin to dell proprietary 8 pin adapter available off the shelf. Its 8 pin atx motherboard connector looks identical to that used by optiplex 7020 3020 9020 but the exact pinout has not been verified to be the same. Dell inspiron xps optiplex precision and vostro desktop systems include a power supply with a built in self test bist feature that helps diagnose the health of the power supply unit.