you will have no issue, that card barely draws more power then a case fan. hopefully you don't plan to play modern graphically demanding games on it.
no clue about the 400w comment but its inaccurate.
this is from the nvidia website:
Minimum of a 300 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amp Amps.)
how the hell can it run on a 220 watt psu?