Weird PC problem

Hi. I have a PC which seems to draw moisture out of the air. With an RH of 65 – 75%, there tends to be water dripping out of the power inlet, and sprayed around inside the box. Has anyone experienced this, and what is the cause/solution ? This PC has a 750W PSU, but an older/lower power machine doesn’t seem to do it. The mains tends to be quite high voltage @ 238 – 240, but the current PSU is from FSP, and rated to 264V.