What happens to power supplies as they age

Quizzical

Hard OCP decided to take a power supply that had been in service for 7 1/2 years and retest it:

http://www.hardocp.com/article/2015/03/09/silverstone_olympia_1000w_power_supply_7_year_redux/6

The brand new performance is unimpressive by today's standards, but very nice for 2007.  So what happened?

To voltage regulation, not much.  It was great in 2007 and still great today.  Even by today's standards.

But everything else went downhill.  A power supply that could once deliver 1000 W at 45 C no longer could.  It couldn't deliver 1000 W at room temperature, either.  It could still deliver 800 W at high temperatures.

Ripple was markedly worse, too.  At 100 V, both the +12 V and +5 V went well out of spec even when delivering only 750 W, a mere 3/4 of the rated load.

For a brand new unit, either of those deserve an obvious "fail" recommendation.  And remember that this was a flagship product from a reputable vendor.  Obviously, the "after 7 1/2 years of use" is a huge mitigating factor, so one shouldn't condemn Silverstone for it.

But this also goes to show, you don't want something that is barely good enough the day you buy it.  You want something that will still be good enough when you'd like to retire it from use some years in the future.  That, of course, is unknowable, and power supply reviews focus on the performance of new units because it's massively easier to measure.  That's not a criticism of reviews; you can only measure the things you can measure, and people don't want to wait 7 years for a review of a brand new product.

There are some major caveats, of course.  What happened to one power supply isn't necessarily representative of what will happen to all others.  It's very plausible that other power supplies might not have ripple get markedly worse, or might have voltage regulation loosen considerably.

And, there is the final recommendation:  there's nothing wrong with keeping a high quality power supply for several years, but you don't want to rely on it forever.  Performance does degrade, and not just relative to newer, better competition.

Pemmin

this is common knowledge

Leon1e

Capacitors start to dry out eventually, no matter of what quality they are, they have expiration date. Thus performance starts to degrade.

Of course, the better the quality the longer the time that PSU works. 

Quizzical

Originally posted by Pemmin
this is common knowledge

It is common knowledge that power supplies get worse as they get older.  But hard measurements to compare a power supply after several years to how it was when new aren't common.