The hidden laptop parts that decide speed, heat, and noise

Laptops are way more than just a slew of powerful components crammed into a tight space (a bit like a tin of sardines!). The CPU and GPU are a big part of it, for sure, but they’re only half the story. The other half is the cooling system, which may be the most vital element of a laptop.

For example, you can have two laptops with the same exact processor that run totally differently. One might sail along just fine while the other slows down under the slightest bit of pressure. Performance really hinges on good thermals here — not just silicon.

To better understand how it all works, I spoke with the experts from Dell, HP, and Acer–including Travis North, a thermal engineer at Dell, who we first chatted with back in 2020! And what they told me was… pretty cool (sorry).

How heat moves through your laptop

Designing a laptop’s cooling system is a complicated business because you’ve got to keep things like size, cost, noise, and performance in mind.

Laptops generate heat. Like, A LOT of heat, often climbing into the 80-100 C range under load. The main culprits creating the heat are the CPU and GPU. And the heat’s got to go somewhere because otherwise performance will drop and, if things get super hairy, the laptop may shut itself down. Acer’s Eric Ackerson, Associate Director of Product Marketing, summed it up so succinctly:

Think of it as a relay race, and the finish line is outside the chassis.

Dell’s Travis North says all of this heat is just a byproduct of energy use. Your laptop is constantly using power to do things (be it spreadsheets, browsing, gaming, what have you), and the heat just comes from that. So when the going gets hot, the cooling gets going. 

Foundry / Matthew Smith

The heat first comes off the CPU and GPU, which sit below a metal plate and a layer of TIM (aka Thermal Interface Material). This material, also called thermal paste or “goop” if you’re like me, helps fill in the gaps between the CPU/GPU die and the heatsink or vapor chamber. This helps reduce contact resistance. 

Even though the surfaces of the CPU and GPU die look smooth at first glance, they’re actually more like tiny mountain ranges up close, according to North. This “goop” fills in those microscopic valleys, reducing what engineers call “thermal resistance” and improving how well heat can travel through the laptop. 

Next up, the heat pipes, which are copper tubes with a bit of liquid inside of them (often less than one cc, according to North). The heat turns the liquid into vapor and then it travels to the cool end where it condenses back into liquid. A wick will then pull it back to the hot end like how a droplet of water spreads out into a napkin, as North put it. This happens really fast in a continuous loop. Vapor chambers work in a similar way, but they just spread the heat across a wider surface.

This whole process is known as phase-change heat transfer and it’s a smart way to quickly move heat out of a tight space. If you need of an analogy, North says it’s kind of like boiling water.

Foundry / Matthew Smith

I asked whether he’d ever seen a heat pipe or vapor chamber fail and what the consequences of that would be. He said he hasn’t seen a failure like that in the past 15 years, as they’re pretty robust in design.

The heat then gets absorbed by the thin metal plates of a heatsink. Those plates increase the surface area, which helps to further dissipate the heat. It gives the hot air “as much metal to touch as possible” before the fans blow it out of the system. 

As North described it, the whole system is basically a series of “handoffs,” moving heat from one component to the next until it escapes. That bigger-picture coordination is key. 

Haval Othman, HP’s Senior Director of Gaming Solutions Experience Engineering, also made an insightful point about the system as a whole. He said that cooling only works when heat transfer, airflow, and chassis design work together as a coordinated system rather than individual parts.

The whole system only works if air can carry the heat away. And this is where the fans take center stage, but not in the way you’d expect.

It’s easy to assume that fans are doing most of the cooling work (I was under this impression for a while back in college), but they’re more like traffic directors in the sense that they guide hot air out of the laptop. That said, the fan design itself is a major engineering focus.

Acer’s Eric Ackerson notes that blade thickness, shape, and efficiency matter just as much as speed–airflow isn’t just about how fast the fans spin. HP’s Othman echoed this idea, saying that it’s not necessarily about fan size or speed, it’s more about how much air is moving and where it’s going.

As Dell’s Travis North explained, even shaving a few millimeters off a laptop’s thickness can make cooling significantly harder by restricting airflow and increasing thermal resistance.

Do keyboard layout or case materials actually matter?

Foundry / Matthew Smith

Some laptop makers make keyboard part of the airflow system. Acer, for example, uses an “air inlet” keyboard on some models to pull in even more cool air from above. But while airflow is important, chassis material matters too.

Aluminum is the kind of material we see in premium laptops. It conducts heat well enough, sure, but it can get pretty hot to the touch. Plastic is more insulating, so it keeps inside while the outside stays at a comfortable temperature.

HP’s Haval Othman also highlighted how much thought goes into where the heat ultimately winds up in a laptop: 

In well‑designed systems, heat is intentionally managed and guided away from high‑touch areas like the keyboard and palm rest, especially movement keys such as the WASD keys, which see constant use during long gaming sessions. This approach may not make the laptop cooler internally, but it makes it far more comfortable to use over extended periods.

Every design choice shapes how effectively a laptop can move heat. So what happens when that cooling system gets pushed to its limits?

How can two laptops with the same CPU end up performing differently?

It’s usually the cooling system that determines how long a laptop can keep going at peak speed and not the processor.

They might start the race on equal footing as far as performance goes, but a thicker design with robust cooling will likely sustain higher speeds for longer periods of time. A thinner laptop is more likely to throttle after a few minutes of heavy use. We’ve actually seen this exact scenario play out here at PCWorld.

In PCWorld’s testing, the bigger Acer Swift 16 AI produced a better result than the smaller MSI Prestige Flip 14 AI+ in our Handbrake 0.9.9 encode benchmark, which forces the laptop’s cooling to kick in. Both laptops have the same CPU (Intel Core Ultra X7 358H, if you’re wondering!), but the MSI probably has less cooling compacity due to its compact body.

All that heat doesn’t just immediately go away, either. Instead, it gets dumped into the room you’re occupying, forcing your laptop to work harder to maintain a safe temperature. North said it’s like running a hairdryer nonstop, which helped me contextualize the impact.

Travis also brought up an important technical detail at this point in the conversation: the TjMax or Thermal Junction Maximum. This is the temperature threshold for the CPU. A laptop approaching that temperature threshold (usually 100 C) will start throttling down. A laptop that exceeds it will shut itself down to protect itself.

Modern processors can safely run up to around 100 C, and hitting that doesn’t mean a laptop is broken–actually far from it. What matters is whether the system can keep on performing without throttling. 

He also touches on how a laptop’s turbo mode can make a laptop run faster and hotter–this mode makes the CPU draw more power. North says a laptop may run about 15 watts (at base frequency), but jump to around 55  watts when it’s boosting away in turbo mode. He says that’s “roughly three times the power for a modest bump in clock speed.” This is why good thermal design is crucial. You’ve got to have the room for a bigger heatsink, more heat pipes, and stronger airflow. 

But some folks think that if a laptop gets hot (even a little bit!), that something’s gone awry.

Why you shouldn’t freak out if your laptop feels warm

Heat isn’t the enemy. It’s really not.

As Eric Ackerson from Acer pointed out, this misconception about heat can be misleading. He calls it the “touch-temperature trap,” which is the idea that a cooler exterior always means better cooling. A laptop that feels warm to the touch is usually doing a better job at moving heat away from the internal components. On the other side of the coin, a laptop that feels cooler might be trapping heat closer to the processor and that’s no bueno.

But, as North explained, modern CPUs are actually designed to run hot, often up to around 100 C under heavy load. That’s totally normal. What really matters is whether the system can hold that performance without throttling too much.

Fans are another area where people tend to get it wrong. While they do play an important part, the heatsink and heat pipes (or vapor chamber!) do most of the work. The fans just help guide the heat out of the system. 

How hot is too hot for a laptop?

Unable to contain my curiosity any longer, I asked Travis about the hottest temperature he’s ever seen a laptop reach.

He reported seeing this CPU’s temp briefly spike up to 114 C (um, yikes). Safe touch temperatures cap at about 51 C, which Dell responsibly follows in its laptop designs. That shouldn’t be enough to burn you.

Closing thoughts

The biggest takeaway? Laptop cooling is absolutely critical. In fact, I’d even argue that it’s the foundation that everything else stands on. Every heat pipe and fan blade is part of a thoughtfully designed system, but it’s complex and usually invisible behind the walls of the chassis. If the heat can’t escape, performance can’t last.