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I have about 6 external devices connected to my laptop, 3 USBs, 1 internet line, 1 earpiece, and 1 for my external monitor.

And i was just curious but does the laptop actually needs to do more "work" when we connect more things onto it?


3 USBs:

  1. Logitech Anywhere Mouse MX

  2. iPhone 4 (itunes not on, just charging)

  3. a laptop cooler (that has 2 small fans)

share|improve this question
Depends on what you connect. When plugging something in every connector, I notice no difference... – Tom Wijsman Aug 27 '11 at 15:20
@Tom heys i've updated the question.. take a look =D – Pacerier Aug 27 '11 at 17:07
Which USB devices? You've got my votes... – Tom Wijsman Aug 27 '11 at 17:10
Im curious as to why this question was closed. Its a legitimate question with a definite answer. – Keltari Aug 27 '11 at 17:19
@Keltari Judging from the time stamps, it was closed before it was edited. – digitxp Aug 27 '11 at 17:29
up vote 6 down vote accepted

It causes more work, but the amount is so small that it is not significant to slow down your laptop.

Let's see some examples:

  1. A USB or PS/2 Mouse

    The mouse is being polled at a constant rate to determine whether it has moved or clicked, these polls don't take much CPU cycles so you will not notice any difference by connecting a mouse to your computer.

  2. An external monitor

    By connecting an external monitor, either Analog or Digital; your Graphics Card needs to render the Desktop of that second screen too. As this is done by your Graphics card which sure has resources free, your CPU won't be affected much.

  3. An internet line

    Your network card drivers would have to handle some incoming packets, but we're talking about headers of some amount of bytes here; it won't be enough to bog down your computer unless you are experiencing a DDoS. And even then, you probably wouldn't notice much except for the internet to be slown down to a crawl.

  4. An earpiece

    Audio is just re-routed, there is barely a difference.

How can you verify this? With a tool like XPerf which allows you to see driver DPCs and Interrupts.

Look at the amount of detail it allows you to see. In the picture below, the video card uses quite a lot (for DWM, not for an extra external monitor). But as you can see most of the things shown have an negligible amount of CPU used. There is no significant slowness shown here apart from DWM...

enter image description here

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wow thanks for the answer ! – Pacerier Aug 28 '11 at 16:52
btw isn't laptop's graphics cards generally lousy? (so it would make a difference if i actually require it to show the display on an external monitor?) i'm using this:… – Pacerier Aug 28 '11 at 16:57
@Pacerier: Depends from card to card, but it kinda scales with what you use the laptop/computer for. So, for people with a less good card that don't game anyway the impact from adding an external monitor will be less noticeable because they need less resources. But still, I would belief that in a low performance setting it would still not be significant enough... To update on your USB devices: The iPhone and cooler will only use power when idle. – Tom Wijsman Aug 28 '11 at 17:31
when you say "will use power when idle" do you mean to say "will use power when Not idle" ? btw the fan is running and the iphone is charging. do you mean to say that once the iphone is finished charging it wouldn't be using power anymore? – Pacerier Aug 28 '11 at 17:38
@Pacerier: Power as in charging when connected but not actually interacting with the computer. So, I mean an idle connection. An iPhone never stops charging (but indeed, it would draw less power when done; but it won't have an effect in terms of CPU usage) – Tom Wijsman Aug 28 '11 at 17:43

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