Overvoltage protection being discussed is on the 3.3, 5, and
12 volt outputs. Table 11 from Intel specs even defines where
and what that OVP must do. There is nothing in a plug-in UPS
- outputting 120 VAC or 230 VAC to power supply - that is
going to over voltage protect those DC outputs. Nothing.
Only OVP that a UPS can provide - limit 120 VAC or 230 VAC.
That will not solve an overvoltage problem on DC output of a
'defective by design' power supply.

J.J. asked:
If a computer PSU fails then I have heard that it may
(or may not) blow the mainboard and perhaps various
other components ...

Yes, if power supply does not have OVP. No if supply does
have the required OVP. No UPS will solve this missing OVP
problem on DC outputs of power supply.

Charles Perry wrote:
"w_tom" wrote in message
...
snip
There is nothing in a UPS that will accomplish the
necessary OVP.

You need to specify which kind of UPS. Some UPS will
provide excellant over voltage protection.

Charles Perry P.E.