Laptops have come a long way over the last several years in terms of both performance and portability. But with more processing power comes more heat, so recent gaming computers are being forced to engineer innovative, compact cooling systems to keep up.
In the last few years, CPUs have been hitting clock speed bottlenecks across the board, moving processor manufacturers towards squeezing more processing cores on a single chip.
This trend is great for the laptop world. On the desktop side of things, CPUs have been stuck at 4 cores for a while now. Lower-power laptops had only 2 cores, which greatly limited their ability in a range of more intensive applications. New lower-power laptops at nearly the entire price spectrum generally pack 4 cores. This is great news for people buying a relatively inexpensive laptop as their primary computer.
Meanwhile, "gaming" laptops are starting to squeeze in 6 cores on many models, and even 8 cores in an elite few. This trend closely follows the same one on the desktop side, where 6 cores are considered the new normal thanks to AMD's Ryzen processors.
Wait a minute. If we're up to doubling the core count, it equates to nearly double the heat, barring other architectural changes (which Intel has been pretty slow at lately). But did laptops just suddenly get twice as thick to be able to dissipate this heat? Not quite- in fact, many new models are getting thinner than ever despite being faster than ever. How's this possible?
Modern CPUs intelligently change their clock speed, called Turbo Boost on Intel processors. They can go up to the max boost clock but will back off if they can't get enough power or are overheating. Generally, you can rest assured the clock will never go below base clock unless something is wrong.
The trend in recent laptop CPU generations is to have a fairly high boost clock but a rather low base clock. The idea here is that a short task, such as opening a program, can be executed very rapidly, with performance close to desktop-level. Once a computationally intensive task starts taking longer on many cores, the CPU will warm up within seconds or minutes. At that point, the CPU will have to slow down as much as necessary to keep it in a safe temperature range- in the case of high-power gaming laptops, 97ºC.
One of my friends purchased an Acer Aspire E15 a little while ago. This was a relatively basic laptop with a lower-power CPU, but it packed impressive specs for the price at the time, including a quad-core processor. The life of this computer came to an untimely end recently, after only a year and a half of operation (naturally, longer than the 1-year warranty!). The apparent cause of death was overheating. They were doing some gaming before it happened- nothing the computer wasn't designed to do. Some components even melted to the motherboard, leaving the SSD unrecoverable!
While this was a fluke, I am suspicious that this model may have had a rather high failure rate. Acer had used the same chassis for years before this one, which was the first model they upgraded from a dual-core to a quad-core. I think it's conceivable the cooling system was designed around a dual-core and was overwhelmed by the hot quad-core.
This brings me to why shopping for a fast laptop can be a maze nowadays. One cannot look at the processor specifications only. The base clock and boost clock don't tell you anything about how a particular laptop model will clock the CPU under various situations.
Using my laptop as an example, my Intel i7-8750h CPU has an advertised base clock of 2.2ghz and a max boost clock of 4.1ghz. Executing task on only one or two cores means it has no problem boosting to 3.9ghz. Once I load up all cores with an intensive task, though, the clock hovers around 3.4ghz. Still not bad at all for a laptop, but certainly less than that max boost clock. The main limitation here seems to be the 60w built-in power limit, which is, again, fair enough for a laptop.
The problem comes in when I engage my laptop's GPU, a 120w GTX 1070. It seems to share heat pipes with the CPU, so things get even slower when both chips are loaded, for instance, when gaming in VR, the main reason I purchased this computer. I saw the CPU was down to 2.0ghz in this situation- even below the "base clock". I found this is because the CPU throttled itself down to 20w.
From here, I engaged in some experimentation. One quick fix I found is propping up the bottom of the computer, helping the intake fans get some fresher air. Doing this boosted the clock up to around 2.5ghz and 27w. At least above base clock now, but still not great.
Fast forward through a number of other configurations, and I found that by directing air from a large fan in the general direction of the intake fans, the performance boosted quite a bit further, to around 3.1ghz and 38w. This setup is somewhat inconvenient but incredibly fascinating that it helps, given the laptop already has rather strong fans built in.
I write this article as a warning, so that you are not blindsided the same way I was, naively thinking:
"The top-tier Intel Core i7-8700k desktop CPU has a max boost clock of 4.7ghz, and the laptop i7-8750h max boost is 4.1ghz, so my laptop is 4.1/4.7 = 87% as fast as a top tier desktop. Who needs a desktop?"
Based on Cinebench testing, my laptop CPU is closer to 45% of the desktop one when under a combined GPU load, which is nowhere near a big of a problem for a large desktop tower to manage. Curiously, the external fan props this up to more like 55%- still no desktop, but an improvement nonetheless. We must temper our expectations of laptops looking at numbers alone.
This is not to say gaming laptops are useless. They still can offer more than enough performance for a wide range of use cases, and are, in some cases, not incredibly more expensive than a comparable desktop. Some laptops can have substantially better cooling systems than others, which, with today's inferno CPUs, directly means they can be much faster. Keep this fact in mind when shopping for your next laptop. Look carefully at independent testing to avoid getting something disappointingly slow, or worse, self-destructive.
Welcome! I'm BradzTech, a Computer Science student at Rochester Institute of Technology. I am passionate about computers and analyzing the latest happenings in the rapidly developing modern field of technology, specifically, using it to help people. I share my thoughts on Twitter and, occasionally, here on my blog. Learn more about me.