Is the socket that you plug in your AC-DC adpater isolated from the case? Whatever is hitting you shouldn't be volts striaght from the socket. Plug your multimeter into the earthed prong of a power socket and put it on the case to see what voltage is going through it. Then you might get a better idea of where to look. :EDIT: If you're not strapped for cash, you could pick up a picoPSU to eliminate the larger exposed PSU. I hope that the 120W it can supply is enough to run the 2 HDDs, board, and processor you have. Plus it's one less thing that will need adequate cooling since those picos are crazy efficient (95% IIRC). You might need a 1 male -> 2 female molex adapter though because I think the pico only has 1 molex plug in it.