Intel issued a warning that the internal memory controller (IMC) of its Skylake processor is exclusively compatible with DDR3L and DDR4 memory. There was some confusion about this as some motherboard vendors have launched Skylake motherboards with DDR3 support but Intel now confirms that regular DDR3 memory is not supported by its processor.
Skylake is compatible with DDR3L with a voltage of 1.35V and DDR4 memory at 1.2V. Regular DDR3 memory kits run at a voltage of 1.65V or more, there are some motherboards out there that support these modules but using them can damage your Skylake processor over time:
If this is the case, though, then why do OEMs such as Gigabyte support DDR3 at 1.5 V on some of their motherboards? And why do others such as Asus and ASRock support DDR3 at 1.65 V? RAM running at these voltages might be capable of operating on the motherboard without causing damage to the board itself, but again, over time it will likely damage the CPU. So if you don't have DDR3L on hand, you are probably better off to go ahead and spring for the more expensive DDR4.
Tom's Hardware also learned that Skylake's IMC does not support frequencies of more than 4133MHz. There are already some DDR4 modules that achieve frequencies of more than 4233MHz, but running at these clockspeeds may result in corruption issues:
RAM kits running at clock speeds above 4,133 MHz will likely encounter more errors than other DDR4, and it is probably best to limit yourself to memory running below this clock speed for the time being. DDR4 at higher clock speeds will become more useful in the future as Intel refines its IMC to support faster RAM, but that isn't likely to happen until a Skylake refresh or the release of Cannonlake.