On Tue, 19 Aug 2008 17:12:56 +0100, "GT"
<ContactGT_rem_ove_this_@hotmail.com> wrote:

>"Mike Walsh" <spam_sucks@bellsouth.net> wrote in message
>news:48AAD88D.AF17147@bellsouth.net...
>>
>> The heat from a power supply will increase as the load increases.
>
>That is what I thought. So a significantly 'over-the-top' PSU for a PC would
>tend to run cooler (due to larger cooling potential) than a
>'pushed-to-the-limit' smaller PSU, which would have its little fan blasting
>like mad to keep up.
>

In addition to what Paul wrote, the difference between a
truely higher capacity PSU and a lower one is that some (in
theory, all) of the heat generating parts are more robust
and able to shed their heat through larger volume (lower
power density) and/or better heatsinking. Therefore, a
better designed higher end PSU could in theory be producing
the same amount of heat as the lower end PSU, but the
individual parts susceptible to heat damage are staying at a
lower peak temp.

However, some PSU these days have very good efficiency
ratings above some threshold like 80%, but if the PSU is
very oversized for the system then that PSU may never reach
that efficiency rating, always operating below it's design
target because the system didn't put enough of a load on it.
Even so, it is still a better margin to have than one
gaining a small percentage on efficiency but being shorter
lived by running closer to it's design limits... at least
that's my opinion, I'm sure some tree huggers will beg to
differ but then they don't want to talk about the waste of
resources or power to produce a 2nd PSU or parts to replace
one that failed prematurely.