Ok thanks for your info. I'm aware Hiper aren't a fantastic make but if it will be powerful enough for 4870 + i5 then I will keep it for the time being.
That Corsair one you recommended, that's only 520w, are you sure that will be enough along with an i5?
In fact, with a very good PSU, you could probably run that with as low as 400 watts (provided you don't have a half dozen hard drives, DVD drives and case fans all running too).
520 on a good PSU is a good spot to be. Keeps the efficiency levels high while not being in danger of hitting peak wattage.