Re: Power supplies and reliability

On 6/2/26 15:47, Joe wrote:
> On Tue, 2 Jun 2026 15:06:20 -0400
> Dan Ritter <[email protected]> wrote:
>
>> David Christensen wrote:
>>> On 6/2/26 07:02, Stefan Monnier wrote:
>>>>> I've seen too many hard-to-diagnose problems that disappeared
>>>>> after replacing a sketchy PSU.  Random hangs and crashes, hard
>>>>> drive errors, video noise, hang on reboot, etc.  I no longer
>>>>> try to go cheap when choosing a PSU for builds.
>>>> Yeah, I'm actually surprised the hardware hasn't caught on
>>>> accordingly: while it's now standard for chips to monitor their
>>>> temperature (and adjust their power consumption if it gets too
>>>> high), I still haven't seen anything comparable that would detect
>>>> and report when the input voltage goes out-of-range (and maybe
>>>> also take steps to reduce the instantaneous power consumption?).
>>>>    
>>> https://en.wikipedia.org/wiki/Lm_sensors
>>>
>>> lm_sensors (Linux-monitoring sensors) is a free open-source
>>> software-tool for Linux that provides tools and drivers for
>>> monitoring temperatures, voltage, humidity, and fans. It can also
>>> detect chassis intrusions.
>> Almost all of those sensors are on the motherboard or on
>> attached cards; you'll frequently get to see voltages from the
>> CPU, but hardly ever does a power supply tell you about its
>> load.
>>
> They are also going to be polled, and will return the voltage they find
> at polling time. What they won't tell you is what various ripple
> voltages are, both the initial rectified mains at 100/120Hz and the
> residual switching frequencies of the various step-down regulators.
>
> Under some combination of conditions, including temperature, the
> combinations of ripple may allow a regulator output to drop out of spec
> for a microsecond, more than enough to corrupt a signal on e.g. a SATA
> line. Further, this may only happen once a week or so.
>
> Increasing ripple voltage is what happens when smoothing capacitor
> electrolytes dry out, which they will eventually do with age.
>
> Einstein allegedly said:
>
>   "Insanity is doing the same thing over and over again and expecting
>   different results"
>
> He had obviously never encountered the Intermittent Fault.
>
I may be al ittle slow upstairs, but how does this differ from

persistence??????? Just asking!      :-)