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Why does it take so long for a computer monitor to change resolution? Why does it take 2-3 seconds rather than, say, 50 ms?

E.g. my current Windows 7 with strong GPU and 24 inch monitor takes 2-3 seconds. Why so long? I know some might say "it's JUST 2 seconds", but come on... Games produce hundreds of FPS, and monitors work at 60 Hz, so what is it that takes so much time?

I remember this was the same in just about any machine I ever worked with.

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closed as not constructive by techie007, Indrek, Oliver Salzburg Oct 6 '12 at 19:19

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Are you using a monitor with DB15 (VGA) connector? Or a digital interface (E.g. DVI or displayport). The latter two should not have a delay. –  Hennes Oct 6 '12 at 15:01
    
I'm using DVI conn. –  Jakub P. Oct 6 '12 at 15:03
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1 Answer

The question is a little broad, but I'll take a crack at this... :)

It's because most/all operating systems with a GUI (Windows for sure) send the applications a message that the resolution is about to change. Things then slow down while these applications make their adjustments for the new resolution, and respond to Windows (or not) that they received the message and that they handled it (or not).

Windows Explorer itself then needs to make all kinds of scaling changes and computations to the actual graphical objects (both visible and not) based on its own needs, as well as the needs of the running applications.

As a comparison, I'd say my Toshiba LCD HD TV takes a little less than half the time as Windows to change the resolutions via the set-top cable box (ie: 720p to 1080p and back), and it's not dealing with anywhere near the amount of calculations your computer's GUI would be performing.

I would also expect some noticeable "setup time" for new resolutions even when dealing with the LCD panel at the lowest level.

Refreshing a display at one resolution over and over based on a clock is a lot easier than changing resolution. As well, since refresh rate is a much more important feature to video devices than quick resolution changes, that's where the research resources are spent on improvement.

Hope that helps. :)

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