-It's a BeQuiet Systempower 700W
-it's from 2008
-It had blown output capacitors on the 5V rail which I replaced in ~2012 as the PC wouldn't boot reliably anymore.
-The same symptoms started developing again in ~2014 so I went ahead and recapped the whole thing with Panasonic FR.
-The PSU has worked fine since except that the PC randomly fails to boot when overclocked (happens once a month or so).
Today I decided to use my tiny Oscilloscope and take a look at the ripple on the 3.3, 5 and 12V rails. My equipment is far from ideal and it was somewhat difficult to include both switching and mains noise in my result but I think I managed to get a relatively accurate estimate of the ripple.
It seems both the 5V and 12V rails are out of ATX specification.
I also tried botching a large low esr cap to the 5V rail, which cleaned the output ripple to 60mVpp.
So what do you think? Would it be ok to leave the PSU as it is or should I do something about it? I could simply add more output capacitance to the 5 and 12 volt rails but there must be a maximum output capacitance specification for computer powersupplies, right? After all I don't want to screw up the whole PC because of a crappy PSU. And besides, the PSU seems to be a real cap-killer - I haven't looked inside but I could bet it has done some damage to the output caps again.