According to intel it may damage the integrated memory controller. The motherboard manufacturers don't have anything to do with the memory controller since it's on the cpu itself so not sure they can say what is or isn't safe. Especially if they're not willing to warranty a cpu should the memory controller be damaged. Some are using ddr3 with their skylake cpu's, it is 'possible' though not sure I'd recommend it. Erring on the side of caution is it worth damaging a $200-300 cpu over $40 worth of ram? There are also folks who choose to oc their skylake cpu using nearly 1.6v core voltage, doesn't mean I'd recommend it. It might be fine, it might be a $300 'whoops'.
I'm not entirely sure how well the comparison works between an lga1150...