Their 500W unit seems impossibly rated for current
capability, has poor airflow for that current rating. It
puts all their spec's into question, it isn't a large enough
unit to produce power claimed and do so with independant
regulation so there would have to be sizable interal loads
or else it was only a representative example.
By that I mean it represents what they can custom design per
a target system which is a known load above the actual
minimum, and yet that still doesn't validate their rating.
Since I have no hands-on experience with these and I don't
recall ever seeing an online review, they are a wildcard. I
would not assume it can actually keep any rails within a
given spec without any load on them, and yet they could
still be primary or wholey regulated based on 5V feedback
which could be of benefit - and yet they also list 0A
requirement for that rail. Something has to give, it is not
at all likely one could randomly load any single rail to the
max they list without having to put a load on any other rail
unless that rail were the 5V and their overvoltage shutdown
had a relatively high(er) threshold than a decent ATX PSU
normally would.
You dont' mention the specifics of your project nor
cleanliness and voltage tolerance required, but offhand I
would look for some old OEM ATX PSU design that has at least
240W continuous rating and no more than 14A 12V current
rating. The higher the 12V to 5V current ratio the more
likely you'd need a load on the 12V rail, unless you did a
modification to the feedback circuit as mentioned
previously.
The easier answer is what you already know, you can simply
add the load to the 12V rail and use just about any ATX PSU,
or of course you could seek a PSU that only had the 5V and
3.3V output instead, some industrial PSU which might be
lower cost at an online surplus electronics 'site. 3
examples:
1) Good current:rail rating, ample reserve current per
rating, downside is it's open-frame. If your project had a
suitable, isolating (from AC high voltage) enclosure and you
didn't need ATX PSU connectors, it's the one I'd pick though
it may not have a remote turn-on logic level signal, rather
would turn on/off by simple switch to AC or your added relay
control, etc.
http://www.excesssolutions.com/cgi-bin/item/ES4113
2) Long and skinny, too big for most uses except a 1U rack
case. Otherwise well suited though it's two small fans
probably run at fairly high RPM producing a bit of noise.
http://www.excesssolutions.com/cgi-bin/item/ES4049
3) Less optimal due to higher 12V current ratio, but
probably still managable, enclosed and not as long as #2,
has ATX connectors and a larger fan which might be more
reasonably throttled back to low RPM if noise is excessive
(but should start out being quieter than #2).
http://www.excesssolutions.com/cgi-bin/item/ES2817
I've no idea how old any of these 3 examples are, nor the
storage conditions of their surplus. Hopefully the contacts
aren't tarnished or corroded but if they're pushing 10 years
old it might be time to overhaul with new capacitors before
deploying for a lengthly period of time... but we dont' know
your project requirements.
Certainly other PSU would do the job, a typical 200W from a
roughly 1989 era Compaq, Dell, Gateway or HP PC PSU would be
a reasonable match as well, somewhat similar to #3 above
would be typical of those. Essentially the ideal PSU from a
PC would be an earlier ATX generation when systems weren't
expected to have more than a half dozen amp load on 12V rail
from 2 or 3 hard and optical drives plus a modest fan... but
again, given some hacking you could ultimately make just
about any ATX PSU work if you reverse engineer and modify
the feedback circuit or put a load on 12V rail.
