No there is such thing as DDR5, tho as I know only the PS4 are running GDDR5.
It isn't exactly DDR5 but it is pretty close to it.
I would only go with that if I am using AMD gpu, I believe Asus has better Nvidia cards.
It is all up to you.
I would go with the ASRock 990fx extreme3 since it has a better quality VRMs.
The Extreme3 has a better clocking then the Pro3 since its analog and not like the the Extreme3 which is has digital PWM.
ASRock 990FX Extreme3 Details vs ASRock 970 Pro3 R2.0 Details in Motherboards