In article .com, "orange" wrote:
Can ATX power supply work when mounted upside down? Its 300W
(Chaintech) but with small load (Amiga 2000).



As others have said, electrically there's no problem. Thermally
it should be OK, just make sure of where all the venting is and
that it won't be blocked - this is probably fine since you'll have
the PC board on the top, against the case, and there's likely
no airflow intended under the board in any case.

My concern, though, is mechanical. My experience with ATX
supplies is that the build quality is unbelievably cheap (not as in
inexpensive, but as in junk). In my wife's office I've had to replace
*every one* of the original supplies in her six ATX machines.

But to the point, power supplies have heavy stuff like heatsinks and
transformers mounted in various ways to the PCB. Bolted stuff is
OK, soldered is problematic. There's vibration from the cooling fan,
plus high-frequency stuff from electrostrictive effects. I'd be worried
about long-term fatigue of solder joints when the vibration is combined
with gravity's unrelenting tug.

I've never seen one fail when installed upside-down, nor have I installed
one this way, this is more a theoretical concern than anything else.
Given the choice, I'd install it with the PCB on the bottom assuming
the orientation of the PC's case allows this.

Steve