I'm in the process of re-capping an old ATX power supply. I decided this one is worth saving because it is early ATX standards compliant, and features the full complement of voltage rails that includes -5V. Bizarrely, though, the PCB silkscreen proclaims it is "ATX Ver 2.3", but there's no way it can be, because that standard revision wasn't even created until 5 years after this PSU was made.
Perhaps a typo, and it is meant to say "1.3".
Anyway, one of the main points of evidence that this PSU was getting tired was bulging electrolytic capacitors. What intrigues me though, is why one particular cap was so much more bulged than the others. I managed to track down a datasheet for it (G-LUXON LZ series) and it seems to be one that is more highly specified than any of the others in the PSU: 3000h @ 105C, high-frequency low-ESR (ESR is specified at 100kHz rather than the usual 120Hz). So why has it degraded the worst?
I traced the circuitry, and it is directly on the output of the +5VSB rail. I guess this means it is likely to have been powered up for far longer periods than the other caps, but is this the sole reason? I don't think it would see anything in the way of transient loads. Would the ripple current rating come into play? It is rated for 1A.
I'm thinking of replacing it with something with a longer lifespan rating - maybe 5000h. Worth it?