For whatever reason I cannot find the amperage specs for AMD's 6450. I was looking into a GT 430, but the min amperage requirements are 22 amps on the 12 volt rail and the cheap power supply I acquired in this machine is only rated for 18 amps, and that's prob pushing it as it is. Just need a card to run streaming HD with HDMI as the integrated graphics in this machine is not cutting it. Was a free machine so I'm not looking to dump too much money into it.
The minimum current and power ratings are for the system as a whole, they tend to figure it out using a Core 2 Quad EE, several hard drives, and a ton of fans to give unrealistically high requirements so people wont run into issues.
What PSU do you currently have? The 6450 requires effectively zero additional power because if you are getting a 6450 i doubt you will do anything that runs it at full power.
If you check the link out to this GT 430, hit details and scroll down you'll see where I got the 22 amp thing. I agree it all seems pretty ridiculous, but I've never had to worry about low-end cards before so I don't really know what kind of juice they require. I wasn't worried about it before, but I just don't want to overload this crappy PSU and have to buy a new one. Wouldn't be the worst thing I guess, just don't want to dump any more money into it than I have to.