So, I noticed my RAM was only running at 2100Mhz, instead of the 3200Mhz advertised.
I did a bit of poking around and it seems you need to enable A-XMP in the BIOS for the RAM to be fully utilised. I enabled it and sure enough, jumps up to 3200Mhz. Always worthwhile to check these things and to RTFM. 😅
Before and after screenshots.