Surprisingly, the card does require less power than NVIDIA's reference GTX 580 which seems to be thanks to the low temperatures and the redesigned power circuitry. Unfortunately fan noise in load is quite high, I would have wished for a better optimization of noise and temps here.
Overall MSI's GTX 580 Lightning Xtreme Edition is a beast of a card, yet it fails to include real gamechanger features over MSI's "normal" GTX 580 Lightning Edition. If you are an overclocker, then both MSI's GTX 580 Lightning and GTX 580 Lightning Xtreme are cards that should be on your short list. Extreme cooling like dry ice and LN2 is welcome, too.