I am seeking to find a replacement power supply that will fit into a Dell Optiplex 990 tower that will be able to power a new Radeon HD 6870 2GB GGDR5 card. I discussed this with the manufacturer and they assured me there was not such a ps that existed due to proprietary fitment of the std low wattage ps that came with the desktop. The sales pitch began. Has any of you ever accomplished this before? Any solutions to email@example.com please. Thx in advance.