I read in a random post that for the same "hardware", laptops causes more jitter than a stand-alone desktop PC, causing more jitter for hard-realtime applications.
I was unable to find any logical explanation of why, for the same hardware, the laptop would cause more jitter than the desktop. By same hardware I mean same CPU, same I/O and same GPU.
If I have to rephrase the question - Is there anything architectural different in the laptop hardware as compared to the desktop hardware (you can choose to answer only for the "CPU" instead of the "hardware" as well) that causes more jitter.

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Jitter of what exactly? Screen luminosity? – Bergi Jul 20 '16 at 10:06
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The power supply and cooling situation is very different between laptops and desktops. – Bergi Jul 20 '16 at 10:11
1 Answers
Today, CPUs constantly adapt their clock speed. If high performance is needed, the clock speed is adapted to the available thermal budget, i.e. if the CPU has a low temperature, it will overclock (turbo mode). As the CPU temperature increases, the clock speed decreases, and may significantly drop below advertised clock speeds. Naturally, cooling is a lot more difficult in laptops (size / thermal capacity of the cooler as well as the amount of moved air / amount of heat exchanged with the environment). Therefore, an airy desktop can keep high clock speeds for longer amounts of time.
Possible hardware differences: In laptops some components (CPUs) are soldered onto specialized mainboards, and due to the confined space a laptop mainboard may be structured differently than desktop mainboards - although this shouldn't technically make too much of a difference. Besides that, a laptop i7 processor may have significantly less performance than a desktop i7, so to make a comparison you need to look at actual processor model numbers.

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Thank you so much. Seems like a logical explanation to what's happening inside. – raghu rajappa Jul 20 '16 at 11:07