So can I have the gt520 in my computer or not plus the gt 520 only us 30 watts max at full load and the gtx550 ti at full load uses 120 watts and the FX 8350 full load uses 125 watts
I don't understand. Your PSU will work with either card, your system probably doesn't draw more than 300 watts right now. Are you wanting to replace the 550 Ti with the 520?