First thing I would do is put the computer back the way it was. Put the old power supply back in, remove the 470, then boot up with the integrated graphics. Once you have the computer working, start over. First, replace the power supply. Do NOT install the 470. Once you have the new power supply installed, boot up using the integrated graphics. Is everything working normally? If no, come back here. If yes, then download the latest AMD videocard drivers, and proceed to install the 470.