I ran the numbers, and while you're way closer than I was, it still seems to me it's way more than 1000. 1 billion bits at 2.85 trillions of watt -> 1 billion

I ran the numbers, and while you're way closer than I was, it still seems to me it's way more than 1000. 1 billion bits at 2.85 trillions of watt -> 1 billion transistor CPU, uses 2.85 trillionths of a watt at 1 HZ -> 1 billion transistor CPU, uses 2.85 thousandths of a watt at 1ghz -> 1 billion transistor CPU, uses ~1/100 watt at 3.5ghz So that puts us at a factor 10,000 away (billion transistor, 3.5ghz CPUs use ~100 watts at peak), assuming that all transistors are on. However, they're not nearly always on. Most are cache, most are logic that's not used, etc. Call it 5 orders of magnitude, or 100,000x. The paper you're referencing seems to ignore leakage current etc, but I don't think for practical analysis of the field you'd want to do that, since obviously other factors are going to be improved as well. Add in how inefficient our modern computation is, in terms of how many bits we're flipping around for the result we're computing, and I stand by my comment; theoretically optimum computation devices are going to make our current CPUs look like abacuses. Though we'll have to break out of our x86 and even CPU model to get there.