Samsung, i think. Not sure. There's only a few ICs right now that can do those speeds, so basically everyone is using the same stuff. I don't think it's really important right now what ICs 8 GB sticks use because of that. I'll pop my G.Skill set into the freezer and pull the heatspeader when frozen, and post some pics, might help ya figure out what Corsair is using. you couldn't pull the heatspreaer anyway..I mean you could, but you'd kill the sticks doing it.