I have a similar issue, I have the dominator platinum, 5200Mhz, and it won't even take the XMP setting, the machine won't POST with XMP on. I have had this before with other Corsair memory, I had a DDR4 Vengeance 3600Mhz kit which wouldn't run at XMP speed on my Hero XII board with an i9 9900k, I mean it'd run at 3400Mhz, but then so would my 3200Mhz kit so you know...But this is really hacking me off, the DDR5 will only run at 4000Mhz, I have a Z690 Hero and an I9 12900k. IDK if it's the memory kit, the board, the BIOS (there has only been 2 BIOS's so far) or my incompetence. Anyone any ideas, someone from Corsair maybe want to chime in.