The voltage converter is for using products of different voltage inputs as different countries have different power grids. However, most modern psus have variable voltage input (no voltage switch like old psus) so converters are not needed. Look at the specs AC Input 100 - 240 VAC, 10A, 50 - 60 Hz
http://www.evga.com/Products/Product.aspx?pn=220-G2-0550-Y1 so the converter is not needed if your country falls in that range which should cover all countries and you can get a cheap adapter. https://en.wikipedia.org/wiki/Mains_electricity_by_country