The Wii U is efficient more than it is powerful. It has things like a digital signal processor for sound, slow memory (likely) and embedded ram to save power. Your GPU on the other had is made to maximise performance with fast and energy hungry chips.

I've never heard of such a small power consumption though. The PS3 60gb consumed 380W at peak and even the latest slim still consumes 190W.

Actually those are the sizes of the power supply. The PS3 consumed a little over 200 watts at launch and is down to around 90 watts nowadays.

I thought they would have had a power supply closer to the max power draw, my mistake.

Yeah me too, why isn't that the case ?

See, Greenpeace? No problems here.

Components ageing maybe? I've heard power supplies lose efficiency over time.

This.

OT:

Doubling the power consumption doesn't give double the performance. Even with the example you gave that's clearly not the case. Yes, the 7870 performs twice as good as the 7770 in 1 or 2 games but in most games it's only 60-70% more. By your logic the 7870 should be at least 3 times as powerful as the 7750 yet the real difference is just a tad over 100% more performance.

I'm not saying the PS4/XBox 8 won't be 4 or more times as powerful but basing that on power consumption is just wrong. Just look at the difference between the GTX 6xx and the AMD Radeon HD 7xxx in terms of performance/Watt.

No, it has no correlation at all because some powerful units require a lot less power than older/weaker models. Depending on where these companies go in the generations tech, it can vary far to much. The power consumption has nothing to determine the graphical output. Not even knowing the die size will help determine that, and this is far more specific.

being 6-8x As powerful as the Wii U means it is 12-16x the Power of the PS3/360 which does not sound right at all seeing how the Wii U is around 2-3x the Power of the PS3/360