|Was installing the ram an easy process or did you have to disconnect things, move stuff around, etc. to get to it? As long as the ram was properly installed it shouldn't have caused anything to smoke. So it's likely due to something that happened while you were inside the case. Could you have done something that caused a short between the motherboard and part of the case?|
It's probably going to be either the motherboard or the power supply and the damage may not be repairable so that you'd have to replace whichever part it is. If you can locate exactly what is burning you'd know what to replace. Sometimes just letting sit there and smoke for a few seconds will let you see where it's coming from.