The ones without ihs are usually the weaker ones . The ones that have the caps on the bottom tend to have better memory controllers . They are also picky in ram . Dual rank dimms are hit and miss . Mine is running. 40gb at 3000 MHz ram . Once I went to single rank dimms . ( Yes you lose like 3 percent performance going from dual rank to single rank dimms but ) You won't notice it . Furthermore as long as you are in dual channel you are fine . Also to others, having all 4 rams slots filled will make it harder to get faster speeds . These chips usually work with 2 ram slots . So there is that . If I take out two sticks are drop to 16gb I can hit 3200 but 16gb isn't enough for gaming these days really .