X870 Steel Legend Idle/Sleep Freezing

Hi all, just wanted to report some issues with a system probably failing due to too large memory. It cannot sleep or hibernate. And it also fails to stay awake even when forced after a few hours of AFK.
I'm disabled with pain and often 'walk' away from my system for unforeseen times, hence I like sleep or hibernate mode, allowing me to return to Blender, Premiere etc. without having to restart and reboot every time.

[Unsolved] X870 Steel Legend + 9950X + 96GB RAM + RTX 5080 ??Persistent Idle/Sleep Freeze

System Summary

Motherboard: ASRock X870 Steel Legend WiFi (BIOS 3.50)
CPU: AMD Ryzen 9 9950X
RAM: 96GB Corsair Vengeance DDR5 6000MHz CL36 (2x 48GB) - Low Profile - 6000 EXPO (High Density)
GPU: NVIDIA GeForce RTX 5080
Storage: Samsung 9100 PRO NVMe
Case: Fractal Design North XL (No physical Reset button)
OS: Windows 11 Pro

The Problem (TL;DR)
The system is unstable during any low-power state. It cannot handle S3 Sleep or Display Off (Idle) without freezing.

S3 Sleep: If sleep is enabled, the system refuses to wake. It hangs with the CPU LED on + Blinking RAM LED.
Idle / Screen Off: With S3 Sleep disabled (set to "Never"), the system still freezes if left idle for 2?? hours with apps open (Premiere/Blender). The screens go off, but the PC becomes unresponsive to mouse/keyboard inputs.
The Reboot Loop: Forcing a hard shutdown often results in a "Green Boot LED" but Black Screen (No Signal) on the next boot, requiring CMOS clears or "blind" cable swaps to recover.

Steps Already Taken

1. BIOS Configuration (v3.50)

RAM Stability: Tested with 1 stick and 2 sticks. EXPO enabled.
Memory Context Restore: DISABLED.
Power Down Enable: DISABLED.
Video Output:


dGPU Only Mode: Disabled.
iGPU Configuration: UMA_SPECIFIED.
Hybrid Graphics: Enabled (To ensure a video fallback on motherboard HDMI).

2. Windows / Driver Adjustments

NVIDIA Power Management: Set to "Prefer Maximum Performance" in Control Panel.
Windows Power Plan: PCI Express Link State Power Management set to OFF.
Fast Startup / Hibernation: Disabled via

powercfg /h off

.

3. Hardware Verification

Verified GPU functionality via Ubuntu Live USB (no hardware failure).
Verified monitors work on other devices.
Reseated RAM and GPU multiple times.

Current Status & Temporary Workaround
Despite the BIOS stability fixes (Disabling MCR/Power Down), the "Idle Freeze" persists when the displays turn off.

My current workaround:

Sleep: Disabled (Never).
Screen Timeout: Set to "Never".
Method: I am forced to manually turn off the physical power buttons on my monitors when stepping away. This prevents Windows from sending the "Display Off" signal that seems to trigger the system freeze.

Goal: I need a solution that allows the system to sleep or at least turn off displays automatically without crashing, as I rely on leaving workflows open due to accessibility needs.