I think we can all agrees ASUS is the culprit here.
As for the comparison, my intuition says eDRAM has little bearing on the ability of the core to overclock. I concede I may very well be wrong, though I think it unlikely that the multiple BW-E CPUs I’ve had hands on have had the exact same results as in the article. The average for stability with Broadwell in general seems to be around 4.2 with anything above being above average.
Going above 4.2 results in huge increases in power consumption and voltage requirements regardless of ASIC quality and stability.
But that really isn’t the point of this topic, so I won’t continue to derail it.
Certain pieces of the core and eDRAM run on the same internal frequency bus so whichever fails first (its the eDRAM) limits the total overclock. That's why the Broadwell E chips can hit 4.4-4.5 and the eDRAM Broadwells cant.