My phone has a quad core 1.5 ghz processor. How does the thing not melt? A 1.5 ghz laptop or desktop needs a fan in addition to a heatsink. How have they gotten around this on mobile chips?
A secondary question. What would be the drawbacks if a laptop or desktop was built using a mobile CPU? And why aren’t they if they need no fan and are therefore quieter?
Smartphones use special processors (usually ARM-based) that are designed primarily for energy efficiency and low heat production.
They also omit many features that are necessary for desktop and laptop cpu’s but irrelevant for smartphones like the pci/sata/expansion bus, external memory bus (most smartphones have the memory and graphics processor built right on top of the CPU), and the like.
Well, in simple terms, the chip in your phone is designed to run off small, low power batteries that fit in your pocket. Every year engineers build chips with smaller transistors that need less electricity to operate then older, larger designs. Mobile chips are designed to use less power and put out less heat.
We can not compare clock speeds of a mobile chip to clock speeds of desktop chip. A laptop or desktop chip will do much more work at 1.5 ghz than a mobile cpu will do at the same speed. To do so, it uses a lot more power and outputs a lot more heat.
Today’s mobile chips can sort of match the performance of desktop chips from 10 years ago (however, they are designed for very different tasks, and direct comparisons are not accurate). Those older chips were much bigger, used way more power, and put out way more heat. Modern chip design is smaller and more efficient, even on desktop machines.
No not smaller.
Each gate - as with each transistor, each capacitor - is smaller.
BUT Modern cpu’s have grown larger
more area - why ?
take more power - why ?
MORE CORES
MORE CPU LEVEL CACHE
WIDER BUSES -
HAVAARD vs Van Neuman Memory
MORE EXECUTION UNITS
MORE PIPELINE STAGES and requisite coordination logic (eg detecting the requirement to stall the pipeline)
There are two specs therefore.
The PDA/phone has only a single core ?
And the average cycles per instructions. Moderm pentiums are doing TWO instructions per cycle. (deep pipelining).
Your PDA may be taking 8 cycles to do one instruction. and only providing one core. About the same GHz… so ?? massive difference in transistor count.
Also intel’s are CISC and there’s an overhead of extra transistors for this drawback of history. ( IBM using 8086 cpu before CISC was invented.)
PDA and phone use the strongARM or equiv, a RISC, which allows a power saving.
Mid to high tier phones these day are dual core. And that’s often just for the application code. Sometimes there are more (possibly less powerful) cores for other functions in the same IC.
Other than that, I agree with most of what’s being said here.
your phone has a relatively small, simple ARM SoC (system-on-chip.) A desktop/laptop has a relatively complicated CPU with many times more transistors. An IC’s power dissipation roughly scales with the #of transistors switching, the frequency of the switching, and if I remember correctly the square of the supply voltage.
put simply, your phone’s CPU is a tiny little thing that dissipates maybe one watt of power. Your desktop’s CPU is a much bigger thing that can dissipate up to 100 watts of power.
it would be very slow. Even though your phone’s ARM CPU is running at a similar clock speed, it’s still a relatively simple processor compared to a beast like a Core i5. The ARM CPU can’t do as much per clock cycle as the Core can. If you want to get an idea of what running a desktop OS on a mobile CPU would be like, try Windows 7 on an older Atom netbook. Anything using Flash or video will bring it to its knees.
They do. For example, search for Minix Neo X5. They’re not powerful enough to run Windows, though. Most run Android.
Quad-cores are the norm at the high end now. My One X has an Nvidia Tegra 3 quad-core, which also has a companion core for use when the phone isn’t doing very much.
There are fan-less processors which are designed for more more robust operation, including displaying 3D graphics. This processor, which is for example, is optimized for digital signage, a challenging requirement.
In my limited experience, boards which based on these chips are optimized for signage players or controllers. I was only concerned about the quality of the video playback so I didn’t particularly attempt to make close comparisons to the processors used in note books.
Signage players are optimized for video playback and are often not based on Windows platforms, which saves on processing overhead.
Such laptops do exist. The main drawback is that they can’t run Windows or OS X. See for example the Google Chromebook.