Desert southwest of the US or the Sahara desert, 125 and dry, your best bet is evaporative cooling, using air washers (direct or indirect) to cool by increasing humidity level (the line follows up to the left on the psych chart), and supplement with yoru standard DX.
Now, if you are in Saudi Arabia/Qatar/Dubai kind of weather with an 83F wet bulb (which I suspect you are) you should be thinking descicant total enthalpy wheels coupled with air cooled equipment.