First, you got an answer.
Second, the GTS 450 needs a 400W PSU with 22A on the 12V rails. You need to open the side of your PC case and look at the table on the sticker on your PSU and see how many amperes are there on the 12V column(s). Your PSU is generic so if you are close to 22A you will need to upgrade your PSU.
don't bump if you don't want your thread get lock. maybe your generic PSU can run the card but if you can don't be cheap with your power supply. save some money and get better PSU
^it really depends on the exact make/model of PSU. Like already said above, most generic PSU's dont produce their rated power continuously and the wattage is not well distributed between the rails.