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Comment by MaxBarraclough | Hacker News Reader

> More machines means more power to cool them

That doesn't sound right. A large number of weak computers, should be easier to cool. A cluster of smartphones can get by with passive cooling, but my laptop cannot.

Apart from cooling, I'm not an expert on this but I don't know that performance-per-watt has to improve as overall power increases. Going with my idea you'll need to power more motherboards, but they'll be less powerful motherboards. (The total number of CPU cores being powered remains the same. Same goes for RAM modules.)

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> A cluster of smartphones can get by with passive cooling

Is that true? My phone gets quite hot if I run a taxing load on it for too long. My, perhaps poor, intuition tells me that phones can rely on passive cooling because of the burst nature of phone use. If you’re utilizing your smartphone cluster, I can imagine your fleet overheating.

> If you’re utilizing your smartphone cluster, I can imagine your fleet overheating.

iPhones survive long sessions of 3D gaming even when wrapped in protective plastic shells. If it was an issue, use a bigger passive heatsink than the one they cram into the smartphone form-factor. You could never do that with a server-grade CPU.

With a high-power CPU, the heat emissions are more concentrated than if we use many low-power CPUs.

My iPhone X definitely gets uncomfortably hot after less than 30 minutes of playing PUBG, and I don't even use a case. To illustrate my point, there are "gaming cases" with fans on them, so it's enough of an issue for companies to market solutions at it.

Ok, let's assume the iPhone's cooling system -- i.e. the metal back of the phone -- isn't adequate for long-running heavy loads. I don't think there's a deeper point behind this. Fit a proper passive heatsink and you're all set.

The Raspberry Pi would have been a better example.

What's expensive, and some time ago became a significant limiting factor in densely packing machine rooms, is removing heat from the room. As long as you can supply cool air to the racks they can take care of removing heat from motherboards and other components.

If cooling systems for machine rooms haven't caught up with modern systems that dissipate more heat, the direction you're thinking has merit. But I doubt there are serious limiting factors here, besides cost.

> If cooling systems for machine rooms haven't caught up with modern systems that dissipate more heat, the direction you're thinking has merit. But I doubt there are serious limiting factors here, besides cost.

I think we agree, but I wasn't really thinking of power-savings as the real motivation here, I was thinking of security.

It seems likely we're going to see a steady steam of Meltdown/Spectre-like security concerns. We can have our cake and eat it -- isolation and all the CPU cleverness there is -- if the isolation between instances is done physically rather than with VMs.

If you go with older CPUs you're gonna have higher loads to execute the same work. Which means more heat.

You'd be right, but I didn't say older CPUs. Take modern server CPUs and reduce the number of cores. May as well go all the way down to single-core.

There's clearly a market for weak, cheap, machines -- Amazon didn't originally offer a 'Nano' instance-type, but they do now.

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