Well if its overheating that means its not enough you need to add more case fans or change your ones for the larger sized ones
I think a new heatsink and some properly applied thermal paste might be a good idea here, and maybe get another side for your PC case, with more vent holes. Also, check if all fans are working properly and installed the right way around.
Yeah, cases do make a differene. By changing from a stock TIME case to a Superflower Rhythmic, I dropped my full load case temperature by 11 degrees, and a further 5 when I added some more case fans.