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Comment by mcpackieh | Hacker News Reader

Virtually all of the electrical energy put into a computer is turned into heat, right? Some of it comes out as visible light from the screen and some tiny portion of it is.. converted into information I guess? But generally a 180W computer is putting out very nearly 180W of thermal energy, as I understand it.

My point is that laptops with 90W adapters can get too hot to comfortably touch, I think at 180W you're well past the point where actually using it on your lap is advisable.

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180W isn't as bad as it seems. I have an ASUS Zephyrus 14, which ships with a 180W charger (and has a full Ryzen 9 5900HS + GeForce RTX 3060, 40GB of RAM) -- under normal use, it doesn't get particularly hot at all. (it never draws more than ~60ish watts)

If you stress-test everything to the max (Turbo Mode CPU+GPU, max power draw, while playing a game at 120fps) then yes, you can draw 150+ watts and it's too hot to safely have on your lap. But you can set it on a table and still use it comfortably. (The keyboard/trackpad never gets hot)

Notably, being able to choose which mode you want anytime is super useful. (I can turn this into a respectable gaming rig at a moment's notice, and it weighs less than a 16' MacBook Pro. I can also flip a switch and it's basically an ultrabook with 7 hours of battery life and silent fans -- or I can run it all day off a tiny 65watt USB-C charger in the office in that mode)

Having a high-watt charger means you have the option to use that electricity, not that you are required to do so.

> My point is that laptops with 90W adapters can get too hot to comfortably touch, I think at 180W you're well past the point where actually using it on your lap is advisable.

You're mixing up thermal energy and temperature. Consider that you can easily burn yourself on a 60W soldering iron, but it'd be quite hard to do so on a 1500W oil-filled space heater.

You could keep temperature down with fans, but my 90W thinkpad has fans so strong it sounds (and feels) like a hair drier and still runs very hot. I'm having a hard time imagining a 180W laptop that isn't hotter than hell.

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.

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.

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.

You’re missing another variable here. In your case it may just be the thermal interface material (TIM) isn’t doing a good job of transferring the heat from the processor onto the heat sinks that the fan blows over.

I’ve had temperature drops of over 15 degrees c by opting for Liquid Metal, everything else being same.

Additionally, loudness is not necessarily correlated with actually moving air. It can often correlate with obstruction to moving air.

You can equip this thing with 4 Thunderbolt ports. Each such port is required to provide 15W to connected accessories, and they have to plan for the worst-case current, which inclusive of the greediest CPU and GPU you can configure this diving board with adds up to a huge (worst-case) power draw.

Also, if the user has a dead battery,they want to be able to plug in and charge, ideally while also doing some reasonably heavy computing. So you again need more power than the laptop itself is using.

This is the one case (AFAIK) where input power isn't being converted to some kind of heat: it's being stored in the battery as energy for latter.

My understanding is that most Framework 16 laptops won't draw anything close to 180W, and only the people who put beefy discrete graphics cards in the expansion bay will have that kind of draw, and those graphics modules will have their own fans to reject heat.

This is true, it would take a fantastic cooling system to make burning 180W on your lap comfortable. However that doesn't make a 180W laptop useless. Firstly if you are charging it when not on your lap you may prefer the faster charging and the heat doesn't matter much if it is just sitting on a table. (Plus more than half of the energy is going into the batter rather than being expelled as heat). Secondly if you are at a desk then it is nice to have the ability to do demanding tasks, even if a lot of your use is well under 180W having the ability to set it down and crunch some data (like letting a video render for a few hours unattended or playing a game with keyboard and mouse) is very useful. Thirdly short bursts of 180W isn't uncomfortable, so it can be useful to have this capacity even if your average is well under 180W.

I would hope that the power management settings have options to limit the power usage/heat output that can be enabled when using it on your lap.

TL;DR yes, burning a constant 180W on your lap isn't good, but having this capability adds many valuable use cases.

Total peak power envelope does not mean it is all being dumped into core components.

If your processor only maxes up to 40w, it doesn't matter if the laptop supplies 200w or 1000w. It won't run any hotter.

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