Upgrading Power Supply for Optiplex 7010 MT

Hi, I have a dell optiplex 7010 mt and i am planning to upgrade the gpu for gaming purpose. I am planning to upgrade the power supply first. Does any modification needed for the pin connecting the psu to the motherboard? I read somewhere that dell motherboard has different pin configuration. I also need suggestions on psu ranging from 500W to 650W. Thanks in advance.