There are several layers of "quality" when it comes to SMPS:
Design is ATX compliant
o parts -- fusing & power filtering actually present on mains-in
o operation -- shutdown on shortcircuit without damage
o failure -- contained failure re no emission of material, excessive smoke
Component quality
o Capacitors -- most common failure in any analog system
---- cheap capacitors = high ESR, low temp rating, poor sizing, poor brand
---- hi ESR = hi Effective Series Resistance = power wasted as heat = shorter life
o Enclosure perforation -- main restriction in PCs are the vents
---- 85-89% of system static resistance is the PSU exhaust fan grill & inlet grill
---- round wire grill can have 7-9x less airflow resistance
o General component quality -- harder to identify
---- choke quality, hi-pot quality, PCB quality
---- connector gold-plated, wire thickness, insulation temp rating
Component layout
o Thermal shadowing -- components shield others from airflow
---- layout is important for cooling, and so reliability
---- hot chokes tight up against capacitors of low temp spec
o Optimal layout for sizing -- of heatsinks to capacitors
---- surface area counts on heatsinks
Fan quality
o Brand
---- Fan tier-1 = Papst/Panaflo/NMB, tier-2 = Nidec/Sanyo, etc
---- PSU tier-1 = PSU with NMB or more commonly Nidec (HPQ/Dell)
o Fan Life = Bearing
---- bearing life depends on bearing type & temperature
------ PSU exhaust fan = hot air heated by Case/CPU/PSU
---- heat & longevity = ball-bearing or fluid-bearing
------ ball-bearing gets noisier with age, fluid-bearing far less
---- best ball-bearings are NMB (quietest), then Papst (same life, bit noisier)
---- best fluid is Panaflo (NMB/Panasonic/Sanyo share patent, but NMB
use it only in the fluid bearing of motors for hard drives which they supply)
So what is a PC-Power-&-Cooling PSU?
Probably somewhat like a Dell or HPQ PSU:
o Make or Buy decision outsources Make to probably SPI/Sparkle/Fortran
---- all the same company
o They specify areas based on prioritisation of gain v cost
---- cost being cost of the uprating vs benefit in warranty/reliability
---- flashy paint jobs are out, better ESR capacitors are in
o Probably 10% higher cost allows 20-70% higher pricing
---- without resorting to gimmicks
Of course, that doesn't guarantee a PSU is better, or that it is any different
than an SPI one or a Channel Well Technology one. Plus failures DO occur.
PSUs are an unusual device in that they don't like shocks in shipping. High
temp burn-in doesn't catch every failure mode re mechanical cycling etc.
Higher quality PSUs will increasingly be those which use thermal & mechanical
modelling - easier than ball-grid-array solder balls, but more beneficial to PC users.
So a lot of factors - the parts that are theirs are the specification.
Offloading cooling from the PSU to case fans is a good idea, since it can lower
the noise level but also lower the internal case temperature - beneficial to all.
The new BTX specification will have the PSU basically cooling the HDs, and
separate fan for the CPU/graphics/RAM/VRM - plus rear exhaust fan probably.
ATX PSUs will work with BTX re physical, and electrical with a cheap adapter.
They are simply moving the 20-pin ATX to a 24-pin connector, that's all.
