First, yes you need to do a complete rebuild kit on the PSU. If your guy did a cap kit hopefully all the necessary caps were replaced. Second at the very least pull the PSU out and reflow the solder on every connector. At the very least, again, clean the pins on the board. A better idea is to replace the pins with new ones (repin the board) and cut out the connectors, one wire at a time while putting each wire into new connectors with a molex crimp tool. Now that you have that done do the next that most people overlook. The board grounds by the metal ground trace on the back and is screwed to the metal it mounts too. Clean the exposed strips around the back of the board very well and shiny. Clean the rails that the board screws too. Then make sure the ground braid is well connected to the metal sheet this all screws to in the back box. If you have a crappy ground it will cause all kinds of mess. If you don't have the tools or know how to repin just try cleaning the pins and reflowing and getting the ground right. If that don't fix it maybe hire someone to come repin and do new connectors.