Summary: I have an HP computer with only a dinky little 250 watt power supply. I have not added to it with a lot of extra components. There have been enough upgrades that I know the power supply is working at its peak. I knew I was never going to add a powerful top of the line video card. I still felt I needed to upgrade my power supply. I did some research and price shopping. A power supply in the 400 watt range seemed to be all I needed. I'm not one to go for overkill.