3 ms·Sometimes you put the resistors above the PCB to facilitate heat exchange with air cooling.by ta988 5y agoSometimes you put the resistors above the PCB to facilitate heat exchange with air cooling.Animats 5y agoIf you're dissipating significant energy in a resistor in a switching power supply, you're doing it wrong.ta988 5y agoYes but that was pretty common in old power supplies. Even good old IBM ones had loading resistors like that.