Mtn1206,  The 1600w power supply does support both 110-240, now the difference is that with the 1600w on the lower voltage will derate the power supply to 800w. As you can see in the list below.   100–240 VAC, 50/60 Hz (1100W)100–127 VAC, 50/60 Hz (1600W de-rated to 800 W)200–240 VAC, 50/60 Hz (1600W) Another key thing is the efficiency, while connected to the larger current,  the 1600W power supply is more efficient. Voltage 10% Load 20% Load 50% Load 100% Load Power Supply efficiency at 115 VAC Power Supply efficiency at 230 VAC Hope this helps.
This may be a silly question and maybe this isn't the best place to ask this, but I really don't feel like calling in to Dell right now. I just want to confirm if the 1600w power supplies on the Dell PE VRTX are 110/220 v switchable like the 1100w's are. That's a simple question but I can't find the answer in writing anywhere I've looked. Thanks.
VRTX 1600 watt PSU voltage