Watts are a unit of energy per unit time. So not like a fixed budget in dollars, but rather a recurring budget in dollars per hour. Obviously, our energy use varies a great deal over time (just as our monetary spending tends to), so we can smooth that out (amortize it) to get a rough idea of our average rate of energy use.

If you use a 400 watt computer all of the time your personal remaining energy budget is 1600 watts. I use a computer around 10 hours a day during the week, and three or four on weekend days (so around a third of the time). Amortized, that means I would be using on average around 133 watts on computing, if I used such a desktop. But I actually use a Thinkpad T420, and its consumption averages out to around 30 watts when in use (so amortized to 10 watts).

First of all, your calculation is completely wrong. 400W * 8h would be 3,2kWh which is a lot less than 2000W * 24h = 48kWh per day that is advocated here.

Second, the Macbook Pro which i use 8 hours a day has a 140W power supply but I'm sure it uses less than 50W on average.

- 50W * 8h = 0,4kWh

- 2kW * 24h = 48kWh.

The laptop isn't going to be the problem! Heating OTOH uses lots of energy so good insulation is the key.

It's shocking how hard of a time people have distinguishing watts from watt hours. Even in a forum aimed at technical people.

I like to use the analogy of fuel tank capacity (kWh) vs. engine output --- horsepower for Americans and most Brits (kW).

Power is a flow, it's the rate of energy usage (or output) over time. More power means higher top speed, or stronger acceleration, or hill-climbing ability, or towing capacity.

Energy is a stock, it's a total quantity of potential. A bigger fuel tank won't make your car any faster, but it will determine how much range you have.

Since appliances, equipment, generators, etc., consume or produce watts of power, it's handy to consider how much energy this represents by simply multiplying watts by time, by default, hours.

Not that shocking. About half of American society was unable to figure out why masks and social distancing were helpful during a pandemic.

Your desktop is not going to spend 8 hours running at max TDP, even if you're gaming or doing CAD work. The majority of that time it will be close to idle, pulling no more than 40w from the wall (and thats if you have a poorly optimized system).

You are confusing the watt and the watt-hour. Running a 2000 watt load for 24 hours will use 48,000 watt-hours (48 kilowatt-hours).

The average person doesn't use desktop computers anymore, hell the younger generation barely use laptops.

Also a high end desktop computer might pull 400 W from the wall while gaming, but that's not something the average person does 8 hours a day. Light work on a desktop computer with a monitor should be around 80 W on average.

> If the average person has a modern desktop there's a good chance it has 400w power supply.

Well, first of all, the 400w is a limit, not a _target_. A computer with a 400w power supply does not generally run at 400w. If it did, you'd notice it; that's not an insignificant amount of heat.

However, more importantly, you've misread the article significantly:

> which pictures the average First World citizen reducing their overall average primary energy usage rate to no more than 2,000 watts (i.e. 2 kWh per hour or 48 kWh per day)

> Run a 400w power supply for 8 hours and you have used 3.2 kwh

So well within budget, then.

That's an astonishingly small minded and fractally incorrect take.

First 400W is peak not average.

Second Wh isn't W. 400W is 400/2000ths of 2000W

Third 500mW can provide a reasonable amount of compute for most tasks as evidenced by my 2 yo phone being a perfectly usable desktop when plugged into a monitor. The 10W to run peripherals vastly exceeds the compute needs and is mostly in the form of light being absorbed by an lcd. Before that I had a 6yo laptop that used around 3-10W including screen. Phone hardware is perfectly capable of gaming, local document editing, compiling, and even running small scientific workloads.

Fourth you're completely ignoring embodied energy, transport and climate control which are the things that actually matter.

Fifth. You can do things that aren't sit at a computer.

Sixth. A high power desktop isn't that common even amongst people who play new AAA games a lot.

Seventh. The attitude of 'we can't possibly deviate even miniscully from having everyone on earth follow my exact lifestyle (even the 90% of people who have no access to it) right down to one particularly wasteful aspect of it that has only been around for fifteen years in its current most wasteful form' is unfathomably small minded and entitled.

On top of misusing watts and watt hours as already pointed out. The issue of computers is the embodied energy in actually producing it. So you're better off just using your existing pc for longer, that will make more difference.

A 400 watt power supply doesn't consume 400 watts by just being powered on. It just means it can deliver 400 watts of power if necessary, sometimes briefly, sometimes continuously.

Much the same as a 400 horsepower automobile isn't generating that output all the time, but can reach a peak output of that amount.

In the case of power supplies, both total capacity and durability are indicated by the power rating. I don't know what current thinking is, but recall when overspeccing the power supply was often recommended for reliability and cooling considerations.

I remember the old recommendation from the early 2000s, but I'm not sure if it's still "a thing". Switched-mode power supplies reach closer to their nominal efficiency rating the more current you pull through them.

I have an anecdote: many years ago when Bitcoin/altcoin mining on GPUs was still feasible I ran a rig with a 335 watt TDP graphics card, and the whole setup measured 360-something watts at the wall outlet. It ran 24/7 for months on a 400 watt PSU, without problems.

I just checked my HP Pavilion business-class desktop purchase a couple of years ago, it has a 180W power supply.

> If the average person has a modern desktop there's a good chance it has 400w power supply.

The average person doesn't have a desktop, let alone a 400w one, it's all phones and laptops these days

Measure is the best way to know how much energy actually used. Let's check your own computer.

400W is, well, 20% of 2000W.

No-one uses 400w computers anymore for working though?

No-one? Really? What do you do with your computer?

I mean, three years ago at work i had a 1000W power unit and even when i plugged a TitanX and tried to learn Deep learning i don't think I used more than 200w/h on average (it's still hot, couldn't put my feet near the CU).

On the plus side, i learned how to install and debug Cuda.

I've never owned a computer that uses anywhere near that. Maybe the family computer back in the early 2000s when computers were shared and had their own room.