On the other hand voltage readings taken through the computer may be
inaccurate since the +3.3V line may power the voltage sensing chip,
and many motherboards now use only +3.3V directly (12V or 5V through
regulator).
Many motherboards now use only +12V directly
If trying to save cost...
o Identify why the fan failed
---- electrical failure within the fan -- parametric failure is rare
-------- more common with simpler drive (more components)
-------- less common with ic drive (less components)
---- failure in power feed to the fan -- check wiring, voltage
-------- failure here may be on the board re variable speed
---- failure due to bearing -- more usually audible
-------- cheap PSUs will cut corners most on cooling
o If fan failed, determine if the PSU still works
---- replace fan
---- verify all outputs correct under full load
---- preferably NOT via using expensive computer parts
So overall I would still replace the PSU...
o Jeantech, Topower (Tagan) etc -- are not so good
o Sparkle/Forton/FSP-Group are ok -- slightly older designs
o Seasonic are much improved -- more recent designs
o Antec is variable -- some designs a little intolerant
Replacing a low quality PSU now is better than repairing it,
only to have to replace it & potentially components later.
PSUs vary in several respects...
o Primary/Secondary capacitor quality
---- both dislike high temperatures -- reduces life
---- both suffer premature failure -- if high ESR
---- low quality = high Effective Series Resistance = Heating
o Vstandby has increased over time
---- fan is non-operational during such time, some heat soak
---- more usually this ends up "warming over" secondary caps
o ATX compliance requires specific tolerance
---- short-circuit, shutdown, remove short, PSU operates ok
---- failures should be contained with limited smoke ejection
o Electrical approval requires certain quality
---- HiPot transformer is vacuum impregnated
-------- common cause of approval withdrawal is HiPot QC
---- varies across the UK/EU re which it is approved in
o Suppression/Filtering is an easy cost cutter
---- each component costs, reduce headcount & save cost
---- filtering is the first area to go
---- holdup time (during brownouts) the second to go
---- multiple voltage rails off one regulator another
---- fixed multiple off one rail, if that rail varies so do all
o Thermal system is another easy cost cutter
---- undersized heatsinks, undersized hi-pot, low spec fans
---- tricks to boost weight of heatsinks yet inefficient design
Look on the brightside - failure was contained vs system.
Many systems will limp along until more spectactular failures.
