PSU warm while off

[perdomot]

I opened up the case of my back up pc and noticed that the psu was quite warm to the touch although its been days since I turned it on. The rest of the case was cool so I unplugged it and after a while, it had cooled to room temp. The psu in my main rig was cool when I checked it so I'm thinking this is a sign of a bad psu. Am I wrong? Why was it warm if not in use?

 

[bliab]

I plugged my workstation into a kill-a-watt and found that it consumes 6 watts when 'off'; this might be enough for the power supply to feel warm. I think some motherboards draw various amounts of power when off for things like alarm and LAN based power-on features.

 

[perdomot]

My main pc is set to wake up automatically at 8:30am and it was cool where as my back up pc isn't set up for that and remained warm. It might be something on the mobo drawing power but I wonder what it is.

 

[Zap]

+5VSB keeps drawing power. How much will depend on PSU efficiency.

 

[perdomot]

So an efficient psu wont draw enough to get warm?

 

[beray]

Everything is relative to what you have, PSUs have +5VSB ratings from ~5W to 15W.

Some motherboards used only 5W from +5VSB standby others more.

 

[mpilchfamily]

There are also some motherboards where the USB uses the +5VSB to help power/charge items while the system is off. So additional power could be coming from an item plugged into the USB port.

 

[God Mode]

It is normal unless all the late model psus I used were problematic. :Q

 

[SparkyJJO]

The server PSUs at work will get quite warm when "off" and actually run cooler when on.