1) Have you made sure that the RAM is in the correct order (Greatest to least) and that the greatest variance of RAM on a stick is by a multiplier of 2? Also, with the ram Problem, test each stick individually, one might be errored, if it is, junk it- the computer might function without telling you there's an error if you've got at least one good stick in. Once you've made sure that you're using nothing but good memmory sticks, put them in one at a time, until one of them starts giving you problems. If it is the ram slot, I wouldn't know how to fix it, I would just junk the board though.
2) For the overheating problem, have you changed the processor recently? Sometimes you can blow up a processor if the bus's are wrong, or it's incompatable with the motherboard, you can get major overheating.
3) Again, with the overheating, try making a heat connection between the heat sink and your case to use it as extra sink material (STRONGLY NOT RECOMENDED)
4) Another thing about the heat, try using a high temp thermometer to check if it's your sound or video card, you might need to Sink/Fan one of these.