Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

The Question

SuperUser reader Jonathan is curious about the hardware differences between tablets and laptops. He writes:

Let’s dig in and see what everyone has to say about the hardware divide between the two.

Then I thought maybe it’s because tablets don’t multitask like laptops can, but some Android tablets can have 2 (at least) apps open at once, and even jailbroken iPads can. While some low end netbooks struggle to run a web browser and word processor.

If you attach a keyboard to tablet you have a laptop, so why do laptops seem to generate disproportionate amounts of heat?

Is the difference between ARM and Intel/AMD chips? If so what is it about the different chip designs that make Intel/AMD produce so much more heat than ARM chips?

The Answer

SuperUser contributor Joel Coehoorn offers this description of the divide:

Chetan Bhargava highlights some additional hardware factors that contribute to the heat:

The other side of this, though, is that the tablet processor is no where near as powerful as a laptop processor, even cheap netbooks. This is why, for example, nearly all tablet operating systems absolutely prevent you from running more than one app at a time, and strictly limit what kinds of tasks apps are able to do in the background.

We are seeing some rapid convergence, though… tablet processors are closing the performance gap with each generation, and chip designers are also working to make laptop/desktop processors more and more power efficient.

Finally, it’s worth noting that not all laptops have cooling fans many of the current generation Ultrabooks have an super small form factor, lower power-parts (like SSDs) and use heat dissipation tricks that don’t rely on fans.

  1. Processor 2. Chipset 3. Graphics 4. Power regulators

1-3 of the above subsystems work at very high speeds. Because these subsystems are clocked so high, the power requirement is very high. High speed and hi power requirements generate a lot of heat in Si. Also, these subsystems use PCIe to communicate and PCIe needs to be clocked to a certain frequency to operate. Multiple PCIe lanes originate from the chipset therefore increasing the power usage and generating heat.

Tablets don’t use high end processors or graphic subsystems. Most of them use ARM core that was developed for embedded market. Such processors don’t use special chipsets or PCIe bus and are not clocked at high speeds as the laptop processors. Hence they don’t generate as much heat.

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