Why is it that my pair of 9600gts each use one power connector but suck 200W each, while a single GTX460 needs two connectors for just 150W?
More aboutgraphics card power
Because they have different designs and architectures. Usually newer gen cards have lower power consumption than the older ones,and GTX 460 has a lower power consumption compared to 2 cards of which are 2 generations older.
But the GTX460 needs twice as many power connectors per card than the 9600GTs, implying that it's using more power, even though it isn't.
You are incorrect. The GTX 460 uses more power than the 9600GT, under load at least. The 9600GT uses about 75w during normal gaming while GTX 460 uses about 120w.
Because of its overall new architecture and design AFAIK. You will see pretty much the same results if you compare HD 5xxx cards with 4xxx cards, for example HD 5870 performs like 2 4870s but has less power consumption and its quieter too.
Ah, the GTX uses more power than I thought - I was assuming that the specified TDP (150-160W) was accurate but it uses closer to 250W when under load.
The TDP should be the max power the card will use at stock speeds under stress testing which will push the card further than it will ever go during normal gaming. Nvidia lists the the TDP of the 9600GT as 96w and the GTX 460 as 160w.