I have no reason generally to touch my (18 month old) Atom HE, but I did a couple of days ago and was surprised that it felt quite warm - I’d guess around 30c in standby mode.
I note the power consumption in standby mode is <0.5w which I’d have thought was too little to produce any noticeable warmth.
In network mode the standby power consumption is <2w
The power_strategy_modes (Power Strategy) is set to Low Power and not Server Mode.
I have one of those power-measuring plugs and I see that the actual power consumption during standby is around 11w-12w which would account for the warmth, but AFAIK it should be using that amount of power when in standby.
Mine is cold to the touch when in standby, so something not quite right there. Server Mode is usually the culprit in these situations, but if that’s switched off, then I’m not sure what’s causing it to be warm.
You could try to usual IT solution of powering it off and unplugging it for a few minutes, then restarting it. Might be that some bit of software has got itself stuck in a loop.