We measured the power consumption of the system at the wall while loading the CPU using Prime95 and GPU using FurMark. We also recorded the power consumption with the system idling at the desktop..
In this test we can see the Alienware 17 consumes very little power when idling, however under load this ramps up considerably. It is still less than a fully loaded desktop PC, though.
ASUS do some great gaminmg machines too, and they cost a lot less than Alienware, but at least Alienware put a lot of effort into the looks as well, which is important.
Great machine, I own one, been using it now for gaming for a month. runs a bit hot on my knee, so I use it more on a desk.
The problem with Alienware laptops, of which I have had many, is the hinges wear out so soon. If anything needs replacing it is absurd at costs.