ASRock B650M-HDV/M.2 RAM Issue with R& 8700G

Hello Everyone - Need some Help.
I just built a system with Ryzen 7 8700G APU & ASRock B650M-HDV/M.2 motherboard.
Using GSkill Flare X5 64GB (2 x 32GB) DDR5-6000 PC5-48000 CL30 that I swapped out from my previous build, that includes Ryzen 9 7900 CPU & ASRock B650I Lightning WiFi Mini-ITX Motherboard.

In the 8700G build I'm having all kinds of issues booting with this same RAM. I have no issues booting when using the RAM at the default DDR5-4800.
It had no issues at all in the 7900 build. In that build I just set the BIOS to EXPO DDR5-6000 & off I went.
In the 8700G build, I've tried:

- booting with EXPO set to DDR5-6000, no other UEFI changes > no boot
- booting with no EXPO, DDR5-6000 manually set with all other settings set same as EXPO > no boot
- booting with RAM manually set to DDR5-5800 or DDR5-5600 at 1.4V > no boot
- all of the above with RAM training set to either enable & disabled
- all of the above plus adjusting timings to more relaxed settings from default 30 & 40 at EXPO to 35 & 45

Is there some magic setting in order to get the 8700G to boot at DDR5-6000 or anything close to that or is it's memory controller just total garbage?

I didn't buy the 8700G to use with stock DDR5-4800 RAM settings. Should I just return it & go back to the 7900? I'd like to have the integrated graphics of the 8700G & avoid a dedicated GPU.

Appreciate any help / suggestions to try.

Thanks.