[vorpalhex]

You have a gap in your understanding of the physics here. Even a 400W laptop can be cool to the touch.

A laptop is hot to the touch because it has hot components (eg a processor running at full throttle) and fails to dissipate that heat correctly.

That is mostly divorced from it's power consumption.

If you ran a large robotic arm off your laptop, you'd be using a lot of watts but making only a bit of heat.

[mcpackieh]

There's no gap in understanding, the only way a 400W laptop can be cool to the touch is if it rapidly dissipates all that thermal energy. That would require one hell of a fan, which is what I said with my hairdrier remark. Even 90W already requires a very noisy fan. A fan moving enough air to keep a 400W laptop cool to the touch isn't realistic to put into the form factor of a laptop, and a fan sufficient to keep even a 180W laptop cool seems extremely dubious to me. It would sound like a vacuum cleaner.

What I was missing is the part where the laptop doesn't consume 180W and a substantial fraction of that power is just passing through the laptop to peripherals.

[cogman10]

Case in point, I’ve driven my desktop computer up to 600 watts and mostly it just puts out a warm stream of air silently.