The manual for my old Gigabyte board is blunt about it: hold the power button four seconds and the system turns off. Not eight. Not twelve. Four, with a note that a shorter press drops into suspend instead. HP's Elite 8300 documentation says roughly five seconds. The Acer Aspire 4830T manual says more than four. Three manufacturers, three machines, one number in the same neighborhood. So when Raymond Chen writes that Windows only notices a forced power-off after eight seconds of holding, and that hardware cuts power at twelve, I have to wonder which computer he is describing.

Here is the puzzle in plain terms. Chen says the kernel watches for a long power-button hold, and at eight seconds it grabs a crash dump before the hardware yanks the cord at twelve. That dump gets filed as a "long power button hold" failure and shipped to Microsoft on the next boot. He should know, since he reads them. But if most motherboards cut power at four or five seconds, the operating system never reaches second eight. No dump. No LPBH class. The feature would be dead code on nearly every desktop in the world.

The comments under the original piece rehearse the same confusion. People report four seconds. People report five. Someone managing a Supermicro and a Dell PowerEdge says both die after about five. Someone else floats that twelve seconds is the Qualcomm-on-Windows default, or a Surface thing, or something integrated systems do outside the normal ACPI path. That last guess has the most pull for me, because it explains how a rule could be true on some hardware and invisible on the rest.

But there is a deeper problem, and it is about whether Windows can even see a long press. ACPI, the interface between firmware and operating system, reports a power-button event as a notification with value 0x80: button pressed. That is the whole vocabulary. There is no release event in the spec, no duration field, nothing that says "the user has been leaning on this thing for six seconds." A patch submitted to the Linux kernel list a few weeks ago makes exactly this complaint about the ACPI button driver, which synthesizes a press and an immediate release because the hardware never sends anything better. If Linux cannot measure the hold, why would Windows?

Maybe it can, through a vendor driver, a chipset hook, an embedded controller that exposes the timing another way. Embedded controllers do all sorts of things behind the operating system's back. Or maybe the kernel is not timing a single press at all. Maybe it is watching for two presses inside some window, which would produce a similar feature without requiring the impossible. Or maybe the eight-second figure is a memory of how the mechanism was designed rather than how it behaves on the machines most of us own.

I am not going to settle it by experiment. I have one Windows machine that matters and no appetite for yanking power mid-write to see whether a dump appears. But the disagreement is worth sitting with, because it exposes something we usually ignore: the boundary between the operating system and the board underneath it is fuzzy, documented in three places that do not agree, and enforced by a microcontroller nobody thinks about. Chen's twelve seconds and my four seconds can both be true if they describe different hardware. The interesting question is how many of those emergency dumps actually come from machines that behave like his, and how many of us are running a feature that never fires.

https://www.osnews.com/story/146273/how-long-do-you-need-to-hold-down-the-power-button-to-turn-off-a-pc/