Probably not, that is the manufacturer recommended wattage without knowing what else you have in your system. Any GPU that doesn't have an external plug doesn't draw more than 75w of power. Unless are running a monster CPU or a bunch of other things drawing power you should be fine with a 300w, assuming it's not the bottom of the barrel. Looks like the 750Ti max's out at 68w. If you want to give the rest of your system specs we can run a calculator to make sure.