What power supply would be compatible?

I been looking to upgrade my desktop with a new graphics card and need a new power supply i have a Lenovo TS140 ThinkServer i3 core was looking somewhere around 400-480 watt s i'm aware i'm going to need a 24 to 14 pin adapter but i wan t to make sure i don't wind up giving something to much power.

You can't "give something to much power", you could use a 1000eatt psu if you wanted. What you should be worried about is will a standard psu fit

It looks like it uses the standard ATX size power supply, so you have plenty of options. What graphics card are you looking to get and we could recommend what wattage to get?