Question Do PSUs supply a voltage when off?

s355

Junior Member
Jun 1, 2021
23
0
6
FFIaT.png
Does the PSU supply a voltage when the "Power" switch is off in this picture? If so, what can I power with the voltage?
 

mindless1

Diamond Member
Aug 11, 2001
8,031
1,440
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Yes, they supply 5VSB which is usually 3A or less, should be listed on the PSU label. You can power anything you want with it but keep in mind that a high load can wear out components in that subcircuit (especially the capacitor(s) ) because the PSU fan won't be running.

If you have that slight a load, you're better off just using PS-On to turn main PSU circuits on and running the light load off the main 5V rail.

You'll lose a little efficiency but gain PSU lifespan and if you really want high efficiency, use a cell phone USB charger instead for this low 5V load. However heat can again become an issue, for a high % /day runtime you will get longer lifespan by drilling several vent holes in it.
 

s355

Junior Member
Jun 1, 2021
23
0
6
Yes, they supply 5VSB which is usually 3A or less, should be listed on the PSU label. You can power anything you want with it but keep in mind that a high load can wear out components in that subcircuit (especially the capacitor(s) ) because the PSU fan won't be running.

If you have that slight a load, you're better off just using PS-On to turn main PSU circuits on and running the light load off the main 5V rail.

You'll lose a little efficiency but gain PSU lifespan and if you really want high efficiency, use a cell phone USB charger instead for this low 5V load. However heat can again become an issue, for a high % /day runtime you will get longer lifespan by drilling several vent holes in it.
You mean turn on the "Power" switch in the image before using any load?