X870E Taichi 0d debug code

what the manual says about this code?

i would reseat the cpu in the socket

The 0d debug code on Asrock boards during reboot often points to an issue during memory initialization or training in the POST sequence, even if the system is stable once booted.
Given your components (new platform, high-speed RAM, 9800X3D) and symptoms, the most likely culprits are related to the RAM and its EXPO profile:
EXPO Instability (Most Likely): The Kingston Fury EXPO profile (6000 CL30 @ 1.40v) might be marginally unstable specifically during the boot/reboot memory training phase, even if it passes benchmarks once Windows loads. This is common with new platforms and high-density kits (2x32GB).
Memory Context Restore/Fast Boot: Sometimes BIOS settings designed to speed up boot by skipping full memory retraining can cause intermittent issues like this.
Troubleshooting Steps:
Disable EXPO: Go into BIOS, disable the EXPO profile, and let the RAM run at its slower JEDEC default speed (likely 4800MHz). See if the reboot freeze issue disappears completely. If it does, the EXPO profile settings are the likely cause.
BIOS Memory Settings: Look for settings like "Memory Context Restore" and "Power Down Enable" in the BIOS memory timings section. Try disabling both, save, and test rebooting (with EXPO still enabled if step 1 didn't apply, or re-enabled if step 1 pointed to EXPO). This forces fuller memory training on each boot, which can solve instability.
Test RAM: Run a thorough memory test like MemTest86 from a bootable USB for several hours (ideally overnight) with EXPO enabled to check for underlying RAM errors.
Update BIOS (Again?): Double-check Asrock's site for any newer beta BIOS or AGESA updates released since 3.20 that might improve memory compatibility.
Manually Tune RAM (if EXPO is unstable): If disabling EXPO fixes it, you could try re-enabling EXPO but manually tweaking timings slightly or increasing DRAM Voltage (e.g., to 1.41v) or SoC voltage slightly (check safe limits) for better stability.
While a hardware defect is possible, intermittent reboot issues with 0d strongly suggest a RAM/BIOS configuration problem first. Focus on stabilizing the RAM settings during boot.