I'd replace the standoffs in the case - I feel as though something has to be shorting, if he's lost a mobo or two already. It has to be shorting, sometimes it will short enough just to cause gate leakage in a few components and over time it will just shit the bed. Even if it shorts enough not to boot, the part will still work for a while if set up correctly. I'd personally just buy a set of extra tall standoffs, put them in and try.