Asus z370-g since Bios update unable to clock Ram above 3,000 mhz despite it being rated for 3200mhz

[Phillip Gwynne]

I have an Asus z370-g with an intel 9900k overclocked to 5.2GHZ, an EVGA RTX2080xc, and 4 x 16gb Corsair Vengeance LPX 3,200MHZ ram sticks (CMK32GX4M2B3200C16). when the bios was on version 2401, I was able to overclock to 3,600Mhz, but since updating the Bios to version 2,800, I cannot get above 3,000Mhz and even that was a struggle. The XMP is enabled, tried setting memory timings to 'auto' tried using the standard timings for this memory which was more reliable for just getting 3,000Mhz but no matter what settings I try and change, when I restart the Orange LED stays on and motherboard will fail to POST. Does anyone have any ideas, maybe there's something I need to enable/disable in BIOS or is this updated version no good? Many thanks in advance