One note many people may forget...
o Your high end decent PSU just failed - out of the blue
---- remember an ATX PSU is on standby, not physically off
---- so primary side surges, lightening etc, can still zap the thing
o A failing bad PSU (as well as the above) can take out a PC
---- ATX spec compliance is advisory not legally binding
---- several PSUs have varying approval in various countries
-------- HV hi-pot insulation being a common rejection
---- consider extra cost of a PSU vs components downstream
Rarely a PSU will take out downstream components.
However that it can should be a reminder about backup importance.
There are only a few PSU makers, a lot of specifiers & relabellers.
o Surge & filter components are often cut
---- hence risk of on-standby PSU damage from surges etc
---- even with those components there is still a small risk
o Actual ATX compliance components are often cut
---- crowbar protection re basic short-circuit protection/recovery
---- two rails off one regulator resulting in shorter life
---- undersized heatsinks & "Wattage Label Uprating"
---- oversize heatsinks, underspec rest & same "Wattage Label Uprating"
So sticking with the key brands is not a bad idea, often they buy from
the same PSU makers - but at least specify to ATX compliance etc.
Antec, Sparkle & similar are ok PSUs - Sparkle tend to be slightly
older designs in some cases, but have been OEM to Compaq etc.
An UPS is very useful in areas prone to brownouts etc.
A PSU is not always the cause, but odd behaviour can be caused by them.
In the past you could get away with largely crap SMPS designs, but the
introduction of ATX "standby" exposed PSUs to higher power-on-hours.
Importantly the higher power-on-hours involved Vstandby of 5V 2Amps,
yet the fan is not running. Some poor designs run quite hot in standby,
that heat can heatsoak low quality electrolytic capacitors which have a
high ESR (Effective Series Resistance = Heating). Result is lower life.
Some designs fit inferior secondary caps thinking the heating is masked,
but that can result in instability at the PC side later on in the PSUs life.
Prescott boards & higher RAM capacity boards impose high demands...
o Prescott imposes high load on the m/b VRM in itself
o RAM capacity was once limited by RAM VRM capability re cooling
PC baseline wattage has risen - Prescott SOI dissipates 50W at idle.
Even a 60W lightbulb manages to create light whilst also at "idle"
Standby convective cooling can be quite poor in some designs, and
the PSU in standby is still exposed to mains (primary) side risk.
Graphics cards can impose very high current demands - idle wattage
on GPUs can be pretty abysmal, and peak wattages can be quite severe.
There are a lot of parts in a PC SMPS, and thus a basic minimum price.
