That being said- you will likely need 500 watts to run the 970. You can get 4 pin to 8 pin molex adapters to plug into the 970's extra voltage connectors. I think most Dell minitowers are like 240-290 watts so I think you won't have enough power.
You can do a dirty hack by buying an aftermarket power supply 500+ watts and then get the required adapter to connect to the Dell motherboard, and unfortunately it will have to sit outside the case since it won't fit. See the picture below- 