The majority of entry level and mid-range servers are configured with 120v plugs even though by design they will work with 120 or 208v. Larger towers and rack mounted servers tend to be configured with 208v.

Why 208v?

The primary reason is for power supply energy efficiency, which is a measurement of the amount of power lost between the input and output of a server’s power supply. You could expect a two to three percent increase in power supply efficiency by simply increasing the input voltage, resulting in a significant saving in power expense. Some have reported as high as a 30 percent increase in efficiency.

This energy savings is significant to any data center’s bottomline.

Can 120v be retrofitted to 208v? Absolutely. Whereas 120v has one hot, one neutral and one ground, 208v simply has 2 hot lines versus one. Do your servers run 120v or 208v? Will your prospective data center customize their existing 120v to match your 208v requirements? These are important questions to ask.

Why is 208v more energy efficient?

For a given amount of power, as the voltage increases, less current is required. Conversely, as voltage decreases, more current is necessary to maintain the same amount of power (what we pay for).

Nice posting! All our servers ran pretty much the 208/210 setting but I never took the time to figure out why

Yeah, great post! Keep up the good work steve!

208v is probably better