That's probably a headcannon question. It would end up being down to your own personal opinion/how you imagine the synth characters behaving or how their technological underpinnings work. For instance, Commander Data of Start Trek: the Next Generation was fully capable of eating or drinking if he chose, but it didn't serve anything other than a social function for him, unless he was consuming a particular kind of lubricant that was beneficial for his internal workings. So it's basically up to you :) .