I've just had a second PC power supply fail in the space of a few weeks - I went to switch on the PC and there's no response, no lights, no boot up, no disk spinning. Both were quite old units in separate PCs sharing a single wall socket via an extension block.
I'm wondering what can cause power supplies to fail. Are there failure modes that could cause them to fail so close to one another. Does switching on the wall socket and then off again quickly cause problems? It's probably just coincidence but I'm wondering what are common failure reasons for PC supplies and what can be done to reduce the chance of it happening?