Is there a way to find out how many watts my computer needs?

[Brumboy]

I'm just wondering if there's a way to tell how many watts my computer is using? So I can work out what graphics cards I can use & computer components before I need to buy a new PSU ect.

Also, do people buy second hand PSU's? Because if I ever want to crossfire in the future I'll most likely need to buy a new PSU as my 530W probably won't handle it, but I don't really want to waste £50 by putting it away and not selling it.

 

[Brumboy]

Oh cheers for that link, perfect !

It's saying my computer is using 272W and with my GTX 460 it's using 380W on 90% load.

If I wanted to crossfire 6950's it will take around 528W, my PSU is 530W..that's damn close haha.