I appreciate people wanting to offer suggestions, but I have exhausted all the options and was really just sharing to vent my frustration with Best Buy.
The problem with adapters is all of them are made for DP to DVI or HDMI conversion, not the reverse. Even active adapters will not run this monitor to it's fullest specs.
The tower my nephew has, with the 745 card, has a generic 300 watt PSU. The 745 uses 55 watts and requires a 300 watt PSU as a minimum. The 760 uses 135-170 watts and a 500 watt PSU is recommended. The 960 uses about 120 watts and a 400 watt PSU is the recommended minimum. It doesn't matter though because that is not an option, unless Best Buy offers to do the work themselves, because I am on the other side of the country.
Another day, and still no resolution from these fools.