I just built a system with a ROG Maximus z690 Hero and an Intel 12900KS. This motherboard came with BIOS version 0702. When running the default BIOS settings (no O/C), I get a stable system. The CPU temps do go up to 90-something degrees and cores max out at around 4.9 GHz, so I know I have some work to do on the cooling system, but that is fine (first thing I'll try is switching out the stock thermal paste on my Z93 with some Grizzly Kryonaut which should make a huge difference).
After updating my BIOS to 1505, under load most of the performance cores get throttled down to 400 Mhz (yes you read that right!) while temps loaf around 60C. I can't figure out any way to get more performance out of the system than that.
My next step is to work my way backwards through the BIOS versions to see where this problem starts, but anyone have any idea what is going on here or what to check?