I don't know much about this but, regarding DD4, the article says on page 7: "upgrading to DDR4 doesn’t degrade performance from your high end DRAM kit, and you

I don't know much about this but, regarding DD4, the article says on page 7: "upgrading to DDR4 doesn’t degrade performance from your high end DRAM kit, and you get the added benefit of future upgrades, faster speeds, lower power consumption due to the lower voltage and higher density modules." So maybe it balances out the power consumption?