According to PC Part Picker (http://pcpartpicker.com/) my system with this graphic card only needs an estimated of 233W.
Therefore, my PSU should be fine, and I do not need to upgrade my it. So the Question is when I look at these graphic card's website, why do they lie me? And how can one know what the True Power Consumption of a graphic card requires?
Also, it wasn't your question, but that is a very poor quality video card compared to the rest of your system. The GT740 is just a rebranded GTX650. With your power supply you could also get a GTX750 or GTX750ti which actually use less power than the GT740.
Thank bccorrupt, this cart can help me in my search. And thanks for the recommendation. But you think the manufacture's website would have Power Consumption details.
The manufacturers can only estimate because they don't know the rest of the parts you are using or the quality of the power supply you pick. Pcpartpicker or another online power supply calculator will work better.