According to several reports from Cebit, Nvidia's GTX 480 will require
quite a bit of juice, as it apparently needs a 600W PSU to get up and
running.
While this doesn't sound like the end of the world, it's worth noting
that we're speaking about a single rail 600W PSU, with a 42 amp 12V
rail to be percise. This could spell more trouble for the green team,
as AMD's 5870 feels quite comfortable with just 600W. What's more,
AMD's dual GPU 5970 requires 650W, just 50W more than Nvidia's single
GPU GTX 480. Obviously, the TDP will also end up rather high as well
and some punters are expecting it to end up over 250W.
By comparison, AMD's dual-GPU 5970 is rated at 294W TDP, while the 5870
and 5850 churn out 188W and 170W respectively. With this in mind it's
hard to see how Nvidia will be able to deliver a dual-GPU card clocked anywhere near the GTX 480. AMD used downclocked RV870 cores for its 5970, but this
approach might not work as well for Nvidia due to higher power consumption and
TDPs.
More
here.