Not really. Capacitors do not fare well in long term storage. They degrade over time if unused. A PSU in use will be better off than on the shelf. John Gerow, director of R&D at Corsair says he writes off any unused caps that have been in inventory if over a year old. I'm sure they will last longer than that, but that's just the quality control procedures of his company. This info he offered in JonnyGuru forum in response to a thread on the topic.