To reset the SMC on a mac desktop you need to disconnect the power cable for a few seconds then reconnect it. I wonder if disconnecting the battery connector on the logic board resets the SMC or you need to use the Shift+Option+Command+Power-button key combination too. I guess disconnecting the battery in macbooks resets the PRAM, as it drains the logic board it from power. Am I right? Also: I heard that the best way to reset the SMC is to try the key combination with the battery disconnected, as was done in older macbooks. Not sure if this makes sense.