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Old 01-22-2018
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Default MTTF

I just found a fan with 490,000 MTTF (56 years)

http://www.coolermaster.com/cooling/...th-controller/

Just for fun, can anyone find something (anything) with a longer claimed Mean Time To Failure

Last edited by ashiekh; 01-22-2018 at 09:42 PM.
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Old 01-22-2018
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Quote:
Originally Posted by ashiekh View Post
I just found a fan with 490,000 MTTF (56 years)

http://www.coolermaster.com/cooling/...th-controller/

Just for fun, can anyone find something (anything) with a longer claimed Mean Time To Failure
Mind the max RPM on that particular model. Just to note.
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Old 01-22-2018
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MTTF & MTBF are not the same thing. Cooler Master is trying to pull a fast one with that by making the MTTF seem like MTBF and essentially inflating the number making folks think they're getting the absolute best of the best in terms of product.
Like wise, that MTTF doesn't list what kind of opperating conditions it is taking into consideration. Thus it could be at 15*C in 0% humidity which would greatly increase the life over a product rated at 40C or 50C even.

EDIT: Should state that the L10 Life is a better metric for them to advertise and go by but its not as common nor will it ever be as big of a number as MTBF so it won't be popular.
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Old 01-22-2018
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It was intended to be light hearted, not serious; hence the word fun.

http://www.dailytech.com/article.aspx?newsid=6404

"Seagate Cheetah X15 series, which has a MTBF rating of 1.5 million hours" (171 years), where the real figure was around 6 years

which proves your point.

Last edited by ashiekh; 01-22-2018 at 11:33 PM.
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Old 01-23-2018
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It's a shame hardly anyone does DMTBF.
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Old 01-23-2018
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Same problem with capacitors; cheap capacitors have a stated MTBF similar to good capacitors, but in that case we got wise and want Japanese stock. Then again 'demonstrated' is possible when one is talking 3000 hrs at 105C; harder when years are involved. By the time we know a particular series of hard drives has a demonstrated MTBF of 6 years, the world has moved on to the next series.

All in all, who would have imagined that a device whose sole purpose is converting AC to DC (Switched Mode Power Supplies) could provide so very much entertainment. Even more surprising perhaps is how cheap they have become, and that they do indeed still last for years.

I'm the sort of person that gets the bust stuff, and fixes it up, so perhaps I should not complain so loudly that there is such a ready supply.

Last edited by ashiekh; 01-26-2018 at 03:29 PM.
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Old 01-23-2018
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Quote:
Originally Posted by ashiekh View Post

All in all, who would have imagined that a device whose sole purpose is converting AC to DC (Switched Mode Power Supplies) could provide so very much entertainment.
And that's why this website exists.
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Old 01-27-2018
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Quote:
Originally Posted by ashiekh View Post
Same problem with capacitors; cheap capacitors have a stated MTBF similar to good capacitors, but in that case we got wise and want Japanese stock.
1. MTBF is something for calculating Failure Rates
2. You are comparing 'Standard Level Lifetime' against Mid Range ones.
3. I wonder wich of those capacitors (same Voltage and Capacitance Specs) might last longer. The 20c one, the 50c one or the 75c one?
I wonder...
Maybe you get what you paid for?

And that's what I hate about those demand for "Wapanese" Capacitors, wich are also made in china.

You compare Teapo SC against Nippon Chemicon KZE.

That a capacitor wich has ~double the lifetime spec should last longer, should be obvious, shouldn't it?
Because the equivalent to Nippon KZE is Teapo SJ...

Just look at the series charts of the companies!
Even if Lifetime Specs are about the same (like CapXon KF and GL), the one thats in the Charts above it might still be the better (and more expensive) one.


Also what most people miss in the Capacitor debate:
The Enviroment the capacitor is used in!

How do we know if the capacitor isn't abused and misused??
How do we know the normal operation temperature of the capacitor?
How do we know the normal operation current the capacitor has to endure??

And now lets compare Teapo SC with Nippon KZE in 2200µF/16V:
Ripple Current: 2000mA - 2770mA
ESR: 30 mOhm - 18mOhm
Lifetime: 3000h - 5000h
Both for the 12x25mm types.
The normally used 10x30mm Tepao SC only has 1700mA Ripple Current rating...

Wich one might last a bit longer? Isn't it rather obvios that according to the data the KZE should last almost double the time the Teapo SC does??


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Most of the Times we are talking Apple <> Oranges...
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Old 01-27-2018
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Obviously, if you compare a capacitor with a longer life time, it will last longer; unless it is a lemon, lemons don't last that long (something Donkey from Shrek might say).

The point is that some manufacturers are exaggerating the MTTF.
Attached Images
File Type: jpg Shrek-movie[1].jpg (62.8 KB, 1 views)

Last edited by ashiekh; 01-28-2018 at 02:34 PM.
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Old 01-28-2018
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Quote:
Originally Posted by Tator Tot View Post
MTTF & MTBF are not the same thing.
...
EDIT: Should state that the L10 Life is a better metric ...
Absolutely, MTBF includes the repair time

MTTF Mean Time To Failure
MTBF Mean Time Between Failures

I tend to use them interchangeably, assuming MTTR (Mean Time To Repair) is relatively short.

But I tend to agree with you that the declared value can often not be trusted.


Using the formula e^(-t/MTBF) for reliability suggests that the L10 (Lethal 10%) life is about 10.5% of the MTBF

Last edited by ashiekh; 01-28-2018 at 08:38 PM.
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