I'm no expert myself, but it sounds like the RAM might be buggered. Replace the old RAM and check if the PC works. If it does, do an internet search for the serial number of the "new" RAM and check if the manufacturer rates it for the M/B of the PC.
Or just beat the hell out of the "Tech", just to be sure. The intermittent failure sounds like the RAM is not rated for the FSB of the PC?
Good luck.