On Sun, 9 Aug 2020 at 02:16, Tim via users <users@lists.fedoraproject.org> wrote:
> Michael D. Setzer II via users wrote: > > So, no clue how the setting got changed?? > > While some may say a dying motherboard battery can be the cause for > CMOS or UEFI screw-ups, there are a plethora of possible causes. > Unless you can get it to happen again, you may never know. Just to go > through a few: > > Even a good motherboard battery may have poor connection to the > terminals (dirt contamination, or poor tension against the metal). I > remember back in the 1980s being told to always wipe down coin > batteries before insertion, and not to get your finger grease on them > afterwards. While the latter is next to impossible without gloves, it > really just means don't contaminate the bits of metal on the battery > that touch the bits of metal in the battery holder. Though we were > also told that sufficient contamination across the batteries own > terminals would lead to it prematurely going flat, I think you'd have > to have particularly mucky hands to be able to do that. > > Random circuitry behaviour when the mains voltage spiked or dipped (the > latter can cause some really odd things without causing damage). Logic > circuitry works by using high or low voltages to represent high (1) > bits or low (0) bits. It's either above or below a threshold. When > power goes down (a brownout) without fully turning off, circuitry can > end up with voltages in an level that's indeterminate. High mains > voltage spikes can outright destroy things, can stress and weaken > parts, or just induce voltages that interfere with operation at the > moment of the spike. > Random hardware faults that only rear their heads under a particular > set of conditions. > > Software glitches that stomp over data in an area they shouldn't touch. > > RAM faults. > The first step in understanding a problem is to focus on easy mitigations and known hardware failure modes. Visual inspection of the system board can reveal toasted parts, green scum indicating corrosion on connections, dust accumulation on cooling fins, bulging capacitors, etc. I've seen drive cables that would fall off the connector under their own weight. Periodically checking cables and memory for secure connections doesn't take long. Checking and replacing the CMOS backup battery is easy unless the battery is soldered to the system board. My experience with linux and macOS (and very different from Windows) has been that filesystem corruption not associated with some obvious issue like a system crash or power problem is more often caused by hardware than by software. Whenever a disk acts up I check cables and run smartctl or vendor tests -- some vendors have accepted smartctl output from a linux or macOS system when issuing warranty return authorizations. It also pays to look for common failure modes for the hardware you use. Some models have well-known failure modes. Examples from my experience are capacitors, power supplies, fans, ethernet (card or onboard), and cables. -- George N. White III
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