Well, if it said it supported it, then it should have worked with the BIOS Setup Menu set to the defaults, which is "auto".
That said, even if you buy from those QVLs (qualified vendors lists) it is not a sure guarantees the specific modules you get will work. When Man can create perfection 100% of the time, then it will be different. But with the density and speed of today's modules, even the smallest imperfection, or impurity in the raw materials can impact how they work. Even if each chip on the stick is within tolerance, when added together the other 7 or 15 chips, the total can push the limits of acceptable tolerances. When added with other sticks, it can push the total beyond tolerances. This is one reason a stick of RAM can pass all tests, but not work when installed.