I was told at Best Buy, I would have to increase my power supply from 250 watts to 400watts. If I got the galaxy GeForce GT610 card,which they suggested to replace my Nvidia Geforce 8300 GS graphics card. I just wanted something to replace my original card with out any added expence of a new power supply, Dynex 400 watt power supply. I have read on other site when using the new power supply some coputers did not work, after the instalation. Can I get a replacement video card without replaceing my power supply?