If your old samsung ram works fine (only using one slot i assume) then it can't be an overheating problem, if you have tried the new ones in the same places and it has crashed.
With just a CPU fan though, you will be getting alot of heat building up, but I wouldn't think that would crash the ram chips again if the old one is working fine.
You will also have a PSU fan (maybe sucking air out) and one on your video card i'd think which is okay.
Though I would think about getting some case fans if your case has spaces for them. Maybe 80mm or 120mm ones, depending on case design (120mm ones will run quieter as they spin slower but cool just as much)
You'll get it sorted