The quad core processors are generally more power hungry than the dual cores as well (if that’s a concern), although certain top-end gfx cards are generally the most power hungry out of a set of given components.
If your new GFX card and CPU will be drawing considerably more current, it’s worth making sure your power supply is up to the task. A lot of people get bent out of shape out watts, but the key factor in a machine that has a powerful cpu/gfx combo, is that’s it’s stable under heavy load (i.e. when running intensive game). Generally, this means the most important thing to check is the how many amps it can handle on the 12volt rail. This is usually written on the side of the PSU as “+12v / 33A” or something to that effect.
A good quality 500W power supply is favourable to a cheap 900W one.
A graphics card, as with any component, will only get near it’s maximum rated power requirement when it’s really being stressed, such as a new game with full HDR lighting. When idle, it won’t get close to that.
You can get the Quad Q6600 for a very sensible amount of money just now. I haven’t done much reading on the new ATI cards mind you.
