This morning my neighborhood experience a brief power flicker. Knocked out the digital clocks and the computers, obviously. Wife’s computer turned on normally, but mine would not boot. It was just sitting there at the POST screen, not doing a damn thing. Beep. Reboots. That’s all it did.
I spent all day at work fretting about having to buy a new hard drive or other faulty parts and the hassle of getting the backups installed. After I get home, I fire it up just to try to diagnose it further, and the damn thing works. I am typing this post on it right now. :dubious:
Posters of this SDMB thread mention intermittent faults and what I also call “self healing”, but don’t really explain the science or tech behind it. I’m knocking on every piece of wood I can find that it fixed itself, but I’m just absolutely befuddled that it can do this.
My question for all y’all - What exactly is happening behind the scenes in the computer where it can shrug off a fault like this and act like nothing happened?
Could be something to do with temperature; I’ve had multiple computers that if they were off for more than 30 seconds, they’d reboot and give me POST beeps until they warmed up good, at which point, I could hit the reset button and they’d fire right up like nothing had happened.
Brownouts/Brief power outages can do weird crap to computers - it isn’t broke until you hard power it down, unplugged for at least 30 seconds, and then turn it back on. Same thing with routers and similar - soft reboot/reset isn’t the same as a power out, complete off and all power to the unit discharged, for whatever reason.
Without getting incredibly technical, most of it is either heat related (too much or too little) or has to do with residual electrical charges in the circuits. Keeping in mind that a computer is literally millions or billions of switches flipping really frickin fast, that residual electricity can lock a circuit off or on keeping the computer from booting past whatever point that switch is a part of. Once that charge has dissipated or at least equalized across the system. Problem? What problem? I’m feeling fine. Let’s play some Solitaire!
With PCs, a restart does not reset 100% of every part of every component & peripheral to a fresh state. Simplifying greatly, it restarts the OS, not (most of) the hardware.
As others have said, following a power failure all sorts of internal hardware or firmware state can be corrupted. Doing a full shutdown, waiting a couple minutes for all stored energy to fade & then trying a cold start is more likely to succeed.
If that doesn’t resolve the issue but the PC works fine hours later, then the cause is almost certainly thermal as suggested above.