"Another effect was slightly more mysterious: The SRAM at the top of server racks had a significantly greater number of transient errors than that at the middle or the bottom of the same racks" from "Elevation plays a role in memory error rates"
networkworld.com/article/2172130/data-center/… Wild speculations from only 2 big fricking computers run at 2 different places, which can include everything from diff humans power&budgets