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I've noticed that when my laptop "recovers" from a hibernate, the screen flashes light-green for a split-second before the computer starts up.

What is causing the momentarily flash?

Is this normal behavior or is it indicating a problem with my laptop's monitor?

More info:

  • There doesn't seem to be anything wrong with the display besides the problem indicated above.

  • I do often hibernate my computer instead of shutting it down.

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1 Answer 1

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I have seen this on 2 different models of laptop. (A Sony Vaio around 2005 and a Toshiba Sattelite around 2008).
I have also observed white, red and blue flashes on various other laptops and desktops.
As far as I know this is just the monitor displaying whatever random content the video-card has in video-memory before the card is properly re-initialized when the system comes back from hibernate.

Some systems keep the video-output switched off until after the initialization is complete. Others don't and therefore may briefly show garbage.

This can't do any damage to the system. It's just a visual glitch.

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I've always wondered why such flashes are always green. –  David Schwartz Jul 2 at 22:09
    
@DavidSchwartz My pet theory: It's either green, red, blue or white. A single (RG or B) color-channel set to full or all of them (white). Possible the memory is initially filled with all bytes on 0xff and then 1 color-channel is opened slightly earlier than the others (assuming a 24 or 32 bit color mode). That would account for it. G+B or G+R would probably also be seen as green if it is brief enough as the human eye is far more sensitive to green than to the other colors. (The R or B component just doesn't register that quickly so we just see the dominant green.) –  Tonny Jul 2 at 22:17

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