Computer is turned off, but PSU remains hot.

[SOSTrooper]

So just yesterday I discovered that on one of my computers, the Shuttle XPC SS51G's PSU (with the Flex ATX PSU) remains hot even after shutting down the computer. If I disconnect the power cable, then it'll eventually cool down, but as soon as I plug the power cable back in, it'll begin to get hot again. It gets hot to the point where I can barely stand holding it (not hot enough to burn, though). None of the other components in the computer remain hot (they all are cooled down after shutdown), only the PSU. I know that is not normal, but what could cause this behavior?

The PSU is an Enhance ENP-2320 200W.

 

[mpilchfamily]

Well that is sure indicating a problem. Time to find a replacement. The PSu should not be geting hot like that.

 

[mindless1]

On some smaller form factor PSU, the heatsinks are either screwed to, or at least resting up against the exterior metal casing of the PSU. This is a deliberate design to shed more heat and in itself is not an indication of PSU malfunction.

That it gets hot with system off merely means the system is using a significant amount of 5VSB power. If your PS2 or USB ports are jumpered to use 5VSB instead of 5V, you might switch the jumper on those to reduce that 5VSB current, but it may still run a bit warm because generally as 5VSB current goes down, so too does efficiency.

The better test of whether you need a new PSU is if a multimeter indicates inappropriate voltages, whether there is any system instability, or if you were to unplug it, open and inspect it, if long term heat has popped any capacitors or made the fan start to fail (which you could replace of course, but that's your call).