Mysterious death

Today my Linux box died.  Cause and nature of death is mysterious (the heat may or may not be a coincidence).  But there’s what should be to a big clue to anyone “in the know“, and I’d like any clues on what hardware short of the entire box might be worth replacing.

I was doing something perfectly normal, when the mouse stopped responding.  It had frozen up completely.  So had the keyboard: ctrl-alt-backspace (restart X11) and ctrl-alt-del (reboot) had no effect.  Pinging it from another box gave no response.  Yet the desktop display was still there, frozen in what I had been doing.

OK, hard reset.  Now it won’t come back: the monitor insists there’s no signal, and the num-lock on the keyboard never even lights, as one expects in a power sequence.  Escalate the hardness of restarts to disconnect from the power and leave for a couple of hours, still the same.

That smells of sudden-death to something in hardware.  So how come the display stayed up when it originally froze?  Surely if it was the processor, motherboard or memory, that would’ve gone at the moment of failure?

Posted on June 29, 2009, in Uncategorized. Bookmark the permalink. 2 Comments.

  1. As I understand it, there’s a framebuffer in the graphics card which a dedicated bit of hardware keeps on reading and sending to the screen in a very tight loop at the selected refresh rate – as long as the memory in the card was still powered, and not corrupt, that hardware will keep on blatting the buffer out to the monitor until you pull the plug.

  2. Things that happen before BIOS/POST include video card, RAM, Motherboard, PSU. Probably best tested in reverse order, starting with a multimeter.

    Some motherboards emit a couple of offended beeps on power-up when the video card has failed.

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