Fanless HYS3C210CS units transfer heat to the aluminum case via a silicone thermal pad. Over time, this pad dries out. Remove the PCB, clean off the old pad, apply a thin layer of quality thermal paste (Arctic MX-4 or similar), and reassemble. Result: 5-8°C improvement.
Multimeter with temperature probe (or an infrared thermometer gun), clamp meter. hys3c210cs power supply hot
Troubleshooting Your Hys3c210-cs Power Supply: Causes and Fixes for Overheating Fanless HYS3C210CS units transfer heat to the aluminum