Typically a PCI slot is good for 75 watts. However if your manual states your small form factor @25 watts, then I guess it's prob correct for that board.
A 5570 is rated at 39 watts, so your MB can't supply it's needs
The 900 MHz version of the 6450 would be the closest(27 watts).
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+1 tourist
If you can do 75watts get a 7750