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Comment by wtallis | Hacker News Reader

For as long as the ultrabook design remains popular (and it shows no signs of waning), the high-end CPU options will be riding the edge of their thermal limits during sustained use. OEMs aren't going to suddenly start over-building their cooling solutions just to help out marginally with a niche use case. As long as we don't get back to the problems from a decade ago with dying mobile GPUs, there's not really anything wrong with having CPUs that boost up to the thermal limits of the system form factor.

If someone comes out with a laptop CPU that can't boost up to those thermal limits, it means the chip's undersized and that vendor will probably need a different microarchitecture for the desktop or server markets.

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> OEMs aren't going to suddenly start over-building their cooling solutions just to help out marginally with a niche use case.

A friend from a laptop engineering company has worked on this exact problem recently. Chinese OEMs are all trying to squeeze 35-45w chips into small chassis now.

To my big surprise, doing so in even thin bezel 13 inch models is not that big of a deal actually. Big OEMs simply were never bothered enough to try that before.

I think my point is that a lot of laptops have been held back (throttled) by the thermal solutions not being able to cope with the heat.

More efficient design will give better perf.

You have to take into consideration what kind of workloads lead to throttling. Laptops are usually not used for the kind of tasks that keep a CPU fully loaded for several minutes or hours at a time. People who do use laptops in that manner are a tiny fraction of the market, and when they experience throttling that does not have any bearing on whether the cooling system of an ultrabook is adequate for the kinds of more typical workloads it is actually designed for.

There have been some ultrabook-style designs that offered inadequate cooling even for fairly normal use cases, but that's a separate issue. Mainstream laptops will be designed around mainstream workloads, and heavier workloads will push them to their limits. Better cooling doesn't come free, and if it doesn't benefit mainstream workloads it's unreasonable to expect mainstream laptops to put more emphasis on cooling capabilities.

> Laptops are usually not used for the kind of tasks that keep a CPU fully loaded for several minutes or hours at a time.

Web developers work hard to change this. Browsing without an adblocker and with Javascript enabled is often enough.

Right. I get the sense that most developers browse with adblock on, but the average user experience is for their computer to be effectively running Prime 95 during regular web browsing.

Sorry, but if I buy a six core laptop, I'm not going to be in the casual notepad user category.

In many laptops, thanks to bad thermals I'd be better off with a 4 core where the thermals can keep up. That's where the 7nm stuff could really bring advantages.

I've been able to load up my desktop six core plenty using e.g Docker and a bunch of microservices. It has a fairly decent 360mm AIO water cooler so stays pinned at max perf. Had a bad cooler before, though, and it really impacted perf and stability.

The point still stands that most people buying these machines are generally not running them at 100% CPU usage for extended periods of time; their usage is much more bursty, with short periods at full power separated by longer periods of idling or low power. This gives the CPU plenty of time to cool down in between bursts.

If OEMs optimize for that use case, I suspect that a more efficient CPU will simply mean that they cut even more corners on the cooling, not that the thermals will actually be significantly better.

It's sad that this is the norm. Aluminum is cheap, a bigger heatsink in a regular laptop (not Ultrabook) should cost what, a dollar more? Yet laptops are never designed for full load for hours. Just "mainstream" use. Even business "workstations" have the same problem. I've had to do hardware mods or undervolting on all laptops. WTF.

If only the industry stopped for one second to pursue angstrom thick laptops designs in favor of more thermally efficient ones. Laptops could have their CPU and chipsets facing downward in contact with the bottom cover entirely made of aluminium, then use a second aluminium made upper shell with small thick fins facing outward that when closed works as a sturdy cover to protect the lid carrying the screen but when opened it could be removed then attached to the lower one to increase thermal exchange with the environment. People obsessed with the thinnest hardware wouldn't touch it with a 20 meter pole but those in need of serious performance and mobility would probably find it interesting.

So, have the bottom cover be the heatsink? That actually sounds brilliant.

HP thinned the ZBook series by turning everything upside down and having the bottom be just a dumb panel instead of the main frame.

Sadly they, once again, used a standard, barely capable heatsink. It will run for days loaded, but it will go over 90 degrees and even throttle, which is unacceptable imo.

"So, have the bottom cover be the heatsink?"

Yes, the upper cover with the fins up should be designed to match perfectly with the lower one when mounted with the fins facing down. Cuts should be arranged so that the bottom cover rubber feet wouldn't prevent perfect surface contact. It would become a fairly large heatsink in which the size and combined thickness would likely be enough to counteract the small fins size and absence of fans. Battery/disk/memory covers on the bottom side would be accessible by removing the additional cover.

"You have to take into consideration what kind of workloads lead to throttling."

I'm driving four displays at work with Windows 10 (two 21.5' 1080p monitors, my laptop flipped open, and an iPad Pro 12.9 connected via USB C running Duet Display) and my idle desktop CPU utilization hovers around 15-20%. Having Outlook and Chrome open gets it into the mid 30s. This is a four core i7 Dell Latitude 7490 with 16GB memory and an NVMe drive that I was given in May 2019.

Yes, all the OS/applications I'm using are resource hogs but I'm not even doing software development - this is all business analyst work. Seeing that the general trend of applications/OS will continue to be resource hogs, let's hope that six core thermal chassis design for 14' ultrabooks is figured out in the next two or three years.

Throttling is what happens when your CPU stays at 100% for a long time. Perhaps you could describe the part of your workload that exhibits that behavior, rather than describe a workload that is obviously not causing thermal throttling?

Throttling is what happens if your CPU overheats which does not imply it's running at 100% for a long time

We're talking about the current state of the real market here, not abstract hypotheticals. Laptops overheating at 30% CPU usage is not a widespread issue in the real world; to a first approximation, the only way to get an ultrabook's CPU to thermally throttle is to keep at least one of its cores completely busy so that the processor stays in its boost state long enough to pump out serious thermal energy. Bursty workloads give the CPU too many opportunities to cool off.

"Mainstream laptops will be designed around mainstream workloads"

Games are a mainstream workload that will cause most laptops to throttle.

"Better cooling doesn't come free"

You could make the heatsink in a Macbook out of Pure Silver, and it would barely move the price.

Meanwhile aluminium costs $1.7 per kilo.

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