X870E Nova D4 on restart/cold boot

Hello, i am troubleshooting freshly built PC, seeking advice and suggestions how to proceed with debugging the issue.

AsRock X870E Nova Wifi occasionally throwing d4 error on powerup / restarts, without clear pattern. Waking from sleep/standby without error.

Hello, so i've been trying to figure it out about a week now - EXPO has been in use twice - just as a one more step towards making it work - tp be clear, BIOS is all at default settings, or in other words, no matter the settings, error creeps in occasioanlly.

Let me list whole system spec first:

Kingston 2x32GB RAM (using default Jedec profile, 4800 MHz)
Asus Prime Radeon 9070XT 16GB OC
Corsair HX1200i
Samsung 9100 PRO NVME as system drive, in PCIE-gen5 slot.

3 more drives, unused, one of them formatted for backups first time today:
- WD Green 2TB NVME (unintialized, unformatted)
- Crucial C100 1TB NVME (unintialized, unformatted)
- WD Blue 500 GB NVME (initialized and formatted on April 22nd '26).
- Win 11 PRO (reinstalled once)

All in a Phanteks Enthoo Primo, with bunch of fans for good airflow - ambient temp 24°C, CPU idling ~44°C-45°C.

This is to be my new dev system (working on large codebase, requiring fast builds and sufficient amount of RAM).
I have been using it very very lightly, as setting up local repo and tooling requires time - i have trusty old 5700x still in use, new one is on another desk.

Once i noticed d4 error first time, figured it occurs on POST only and have restarted, turned it off, left it unplugged, left it in standby for many many times in order to see if there is a pattern - no obvious pattern, sometimes it fires up, sometimes no go. I do have useful info as i have gone over three different BIOS versions.

I was always using AsRock driver updated and AppShop to pull correct drivers.

Mainboard originally came with BIOS v3.40. (i have bought everything back in December 2025, but due to various circumstances only found the time last week to assemble everything).

So i have tried following BIOS versions:

- v3.40 (had it originally)
- v4.10 (made d4 error popup MUCH worse)
- v3.50 downgrade, and what i am using now - error creeps in way less often

I'll list now what i have tried so far. BIOS settings are always assumed to be Default/Auto unless stated otherwise. I'll also note which BIOS versions where used for steps listed.

- (BIOS v4.10) reseating RAM (always two sticks, have yet to try using single stick or A1 / B1 slots)

- (BIOS v4.10) - tried to turn on EXPO, in order to see if that might actually solve issue, with manual SoC voltage (tested values: 1.05V, 1.1V, 1.15V, didn't change behavior, made d4 happen more often, with VCore Auto setting going wild in Windows (up to 1.35V)

- (BIOS v3.40) Limit TDP to 105W setting - no observable difference to d4 occurence

- Upgrade BIOS to v4.10 - first boot after upgrade, training phase (code 15) took quite a long time, but it booted

- (BIOS v4.10) - Default/Auto settings - d4 error occurs quite often

- (BIOS v4.10) Manual SoC voltage to 1.10V, limit TjMax to 85°, LLC 2 (default 3) - made d4 occurence worse, especially lower voltages, but decided manual SoC

- (BIOS v4.10) Power Supply Idle Control set to Typical Current Idle - doesn't seem to have effect on d4 occurence

- (BIOS v4.10) Memory Context Restore - disabled, Fast Boot - disabled - this made it occur less often, but still it occured.

So all of the above, it would randomly occur on restart or cold boot, but often enough to be an obstacle - when noticed it first and informed myself about it - i started to restart or power it off / turn back on quite often during past days in order to try figure out if there is any pattern.

====================================================================
Now onto final thing, which made it occur way way less:

- downgrade BIOS to v3.50 - first boot after upgrade, training phase (code 15) took much much less time, compared to first training v4.10 BIOS took)

- (BIOS v3.50) - Default/Auto settings - d4 error occurrence rare, compared to v4.10

- (BIOS v3.50) - Memory Context Restore - disabled, Fast Boot - disabled - d4 error occurence rare.

So net total is with BIOS v3.50 i have way less occurences of d4 error, almost to the point i thought it is resolved.
When it first creeped in, i went into BIOS and disabled Memory Context Restore and Fast Boot - believing that would finally resolve the issue, but it did creep back in.

Finally, when error occurs, what i have found is: system will boot almost always next time when pressing Reset key.
Cycling power when error occurs, system usually won't boot. Both of these apply to BIOS v3.40 and especially to v4.10, because i had most errors happen on those two - with v4.10 being the one where i had by far a ton of them.