How do i know if its time to change the power supply on my computer?

when it wont turn on. or if u wana put in a new graphic card that needs more power, then u will need a new psuHow do i know if its time to change the power supply on my computer?
You don't change it, if it is working don't try to fix it.How do i know if its time to change the power supply on my computer?
when u are trying to run a strong graphics card, or if its not working all together, otherwise there is no reason to change

music player

keyboard and mouse clash up