GTX 680 4GIG model and power requirements (MP 4.1)?

I simply must have 4G VRAM on my next card. I'm ready to buy next week.

Does the GTX6804G version require extra power? I've got the 2009 MP and it's almost maxed out (drives/PCI).

I'd be replacing an existing.

Also: Since the 2Gig version now is fully supported in 10.8.4...can we say the same of the 4G version?