Subj : Re: Pi-FAN for RPi4 with 4 (instead of 3) cables? To : The Natural Philosopher From : Michael Schwingen Date : Tue Dec 10 2024 19:30:23 On 2024-12-09, The Natural Philosopher wrote: >> https://www.rs-online.com/designspark/why-l10-life-expectancy-is-key-for-fan-durability-over-mtbf-ratings > > This is full of bullshit > > "MTBF estimates the lifespan of a fan’s electronic components, expressed > in millions of hours. In contrast, L10 Service Life, measured in > thousands of hours, is based on the durability of the bearings and > lubrication grease." > > So a fan with no electronic components has no MTBF? remove "electronic" and it makes sense. >> https://www.digi.com/support/knowledge-base/understanding-mtbf-mean-time-between-failures >> > > > "Furthermore, MTBF specifically excludes wear-out factors" > > > Total crap. No. Again, MTBF characterizes failures during normal service life. Take a fan which usually fails after 5 years of operation due to wearout, which happens on all of those fans after about the same amount of time - those 5 years are *not* parts of the MTBF. MTBF characterizes the statistical mean time between failures *during* those 5 years due to *other* reasons. So you can have a MTBF of 50 years, and a lifetime of 5 years. If you take 100 of those fans, you can expect 2 failures per year - but after 5 years, the failure rate will rise rapidly to reach 100%. > What matters is how long the repair or the new fan will last. Not > splitting hairs over MTTF versus MTBF The important thing is to keep MTBF and lifetime separate - both will lead to failures, but are separate mechanisms. cu Michael -- Some people have no respect of age unless it is bottled. --- SoupGate-Win32 v1.05 * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3) .