Larry
Computer power supply capacitors - generic question

had a cheap PSU where the 16V capacitors for the +12V rail were getting 50V
peak spikes, but I saw nothing that high in a better PSU's +12V.

From one who has replaced a lot of capacitors.

DC voltage plus signal voltage/ripple times two. In your case DC plus ripple
times two. . Use milspec capacitors. I suspect the computer grade thing is more
marketing hype than anything else.
Bob AZ