A6 error X870E Nova WiFi after BIOS 4.04

Subject: Critical Regression: No POST with any memory frequency (code A6) on X870E Nova WiFi after BIOS 4.04 ??works only on 3.50

Dear ASRock Technical Support Team,

I am experiencing a severe compatibility regression that makes my system completely unbootable with BIOS versions 4.04 and newer. I kindly request your investigation and assistance.

System Configuration:

Motherboard: ASRock X870E Nova WiFi

CPU: AMD Ryzen 7 9800X3D

Memory: Kingbank DDR5-8400MHz 24GB (2x24GB, Hynix M-die)

BIOS versions tested: 3.50 (working), 4.04, 4.07.AS01, 4.20, 4.43 (all failing)

Problem Description:
With any of the newer BIOS versions (from 4.04 up to 4.43), the system fails to POST and halts at debug code A6. This occurs regardless of memory settings ??even at completely default JEDEC frequency (4800 MT/s), with no XMP/EXPO profile applied. The system does not even reach the BIOS setup screen; it hangs immediately during memory initialisation.

Important details:

I cannot enter BIOS to change any settings (voltage, timings, ProcODT, etc.) because the POST process stops before the UEFI interface appears.

Clearing CMOS, removing the battery, and testing each memory module individually in every DIMM slot did not help.

The only way to recover the system is to flash back to BIOS 3.50 (using USB Flashback), after which the system boots and runs stably at any frequency, including the rated 8400 MT/s.

Regression Timeline (confirmed by multiple rollback tests):

BIOS 3.50 ??fully functional, boots with any memory setting.

BIOS 4.04 ??first version where the issue appears; no POST, hang at code A6.

BIOS 4.07.AS01 ??same failure.

BIOS 4.20 ??same failure.

BIOS 4.43 ??same failure (latest as of writing).

This is not an isolated issue:
I discovered the rollback solution through online community discussions, where many users report identical behavior. Multiple sources confirm this is a widespread problem affecting ASRock X870E Nova WiFi boards with 9800X3D and specific memory kits (particularly 24GB/48GB modules):

Overclock.net ??users report that "any 4.XX BIOS does not work... however any 3.XX BIOS works" with the same A6 POST code.

Zod.kr ??a user reports updating two PCs from 3.50 to 4.03, both getting stuck at code A6, and having to roll back to 3.50. The same thread notes that "with 24/48GB memory (Kingbank 24x2), booting fails" on ASRock 4.03.

Quasarzone ??a user with identical specs (ASRock X870E Nova WiFi + Kingbank DDR5-8400 24GB x2) reports that "after 4.xx BIOS versions, black screen occurs... even the 4.07 beta with 'memory compatibility improvement' still shows the same black screen issue".

ASRock forum ??multiple threads document the X870E Nova WiFi getting stuck at A6 after enabling EXPO or updating BIOS.

According to community tracking, there have been 183 reported cases of Ryzen 7 9800X3D failures on ASRock AM5 boards, with ASRock officially acknowledging widespread Ryzen 9000 boot issues and releasing beta BIOS 4.07.AS01 to address them.

What I have already tried (none worked):

Flashing each BIOS version multiple times via Instant Flash and USB Flashback.

Resetting CMOS (jumper and battery removal) after every flash.

Booting with only one memory module installed, in each slot.

Disconnecting all peripherals (drives, USB devices, GPU ??used integrated graphics).

The problem persists in all cases, and the system only becomes operational after reverting to version 3.50.

My request:

Please investigate why this memory kit (Kingbank 8400 24GB) fails to initialise on BIOS 4.04 and later, even at default frequencies, and consider releasing a fix that restores basic boot capability.

Since I cannot access the BIOS, any workaround requiring manual settings is not applicable ??I need a firmware update that allows the system to POST with this memory.

I am willing to provide any additional logs, SPD dumps, or hardware details if needed.

Thank you for your attention to this critical issue. I look forward to your response.