Better late than never
The H570 and B560 can overclock RAM now...but seems CPU's are still locked...and you have to have an i5 or higher CPU. anything lower and you can't go past 2666mhz.
it seems weird to do this as if you can't boost the CPU, I don't see people enthusiastically overclocking their RAM beyond the XMP profiles they can enable in the BIOS already.
Z590 motherboards hit the scene with native PCIe 4.0 support
and here you get the deets on the Z590 and mention of 45 boards that are coming.