Fitted the new PSU yesterday and no suddden switch-offs since, but still early days. Program still shows extremely low voltages so maybe it is not compatible with my motherboard.
Electrolytics on the MB are all SMD, Electrolytics in the old PSU are conventional but none are domed or leaking.
However a low-level high-pitched whining noise has now disappeared.
Possibly the 460 was capable of the task but a flaky fan in the PSU was causing the temp to rise and cause the sudden switch-off ?
Dry joints in the PSU circuit-board are also a possibility, but it is single-sided so I will have to dissect the PSU to check that
> > Ran a program that could report the system voltages and they were all low. The 460W
> > PSU may be on the limit for this system so I have ordered a 600W model.
> > IŽll report it if this fixes it or not.
> Yeah, if all the fans turn and are clean then low voltage seems likely, with bad
> motherboard caps a close second. For power supplies, always buy ones that pass the
> HardOCP.com torture test - cheap Chinese junk (which unfortunately is sold under a
> lot of otherwise reputable brands) frequently only puts out half its rated wattage
> before the voltage sags and the magic smoke starts coming out.