Is this a laser engraver you're running with those NEMA 34 motors? It seems they're oversized for that purpose. But that's probably as high-powered a power supply as the G-540 can handle. Have you looked for mechanical issues? Is the enclosure getting too hot? Issues that happen at the end of a long run can often be traced to overheating. Is the Gecko board heat-pasted to a heat sink with a fan blowing on it?