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.

Sleep/wake issues are a nightmare to deal with. Most repair stores I know just
disable the function when customers bring in PCs with issues to do with it.
The problem is that it could be anything from the BIOS to power issues to the OS
itself. Troubleshooting is almost impossible and more often than not, the issue
comes from Microsoft and some badly written, rushed update. I can't count the number
of times a windows update broke my sleep and/or hibernate function.

One thing I tend to do when dealing with issues like this is create a linux live
boot USB and test under something like Ubuntu (well maintained distro). If it
works under linux then the issue is with windows.

Sorry I can't offer more tips.

Looks like my problems are hardware related, my system has gotten progressively worse.
At first when I did get it to boot into bios it was in bios for a few seconds before it just froze. keyboard and mouse input stopped working, and the clock stood still.
Now I'm at a point where it won't even boot into BIOS at all anymore, the loading screen never shows up, not even bare metal.

I've also succeeded in updating to the latest bios rom released on the 22nd via the flashback method. But the results stay the same.

Here's the summary I've made that I'll send to ASRock.

Subject: Urgent Help: X870 Steel Legend + 9950X ??Progressive Failure to "Green LED / No Video" State

System Specifications:

[] Motherboard: ASRock X870 Steel Legend WiFi [] CPU: AMD Ryzen 9 9950X [] RAM: Corsair Vengeance RGB 96GB (2x 48GB) DDR5-6000 CL36 (Model: CMH96GX5M2E6000Z36) [] GPU: NVIDIA GeForce RTX 5080 (Currently removed for troubleshooting) Storage: Samsung 9100 PRO NVMe (Currently removed for troubleshooting)

Description of Problem: I am experiencing a total system failure that has degraded progressively over the last week. The system has gone from perfectly stable under heavy load to a state where it now POSTs to a Green LED but outputs no video and has no USB functionality.

---

1. Timeline of Failure (Progressive Degradation) This system was not dead on arrival.

[] Phase 1 (Perfect Operation): For the first 2-4 days, the system was fully stable. I used a multi-monitor setup and ran heavy workloads (Adobe Premiere, Blender rendering, and Gaming) to benchmark the Ryzen 9950X against my old PC. It handled high stress on both CPU and GPU perfectly. Note: I used default BIOS settings + EXPO 6000. No manual overclocking was ever attempted. [] Phase 2 (Idle Instability): The first symptom was a failure to wake from Sleep/Hibernate states, requiring a hard reset. [] Phase 3 (Load Instability): The system began freezing during active workloads and eventually froze during the Windows boot animation. [] Phase 4 (Total Failure - Current State): The system now POSTs to a Green Boot LED but is completely unresponsive (Black Screen).

2. Detailed Symptoms (Current "Zombie" State)

[] The Boot Sequence: CPU Red LED (Solid) -> DRAM Yellow LED (Blinking) -> BOOT Green LED (Solid). [] The Failure: Despite the "Green Boot LED" indicating a successful POST, there is NO Video Signal (via dGPU or iGPU) and NO USB power to peripherals. The system logic believes it has booted, but the I/O interfaces are electrically dead.

3. Troubleshooting Steps Taken (Ruling out other causes) I have performed extensive isolation testing to confirm the issue is not the peripherals:

A. Bare Metal Isolation

[] Removed the Dedicated GPU (RTX 5080), all Storage drives, and all USB devices. [] Connected Monitor directly to Motherboard HDMI. Result: Same behavior (Green LED, No Video).

B. RAM Permutations

[] Tested with single RAM stick in Slot A2, then Slot B2. [] Result: Identical failure in all configurations.

C. BIOS Flashback (Critical Test)

[] I successfully performed a BIOS Flashback to the latest version 4.03 (AGESA 1.2.7.1) using a FAT formatted USB stick. [] The Flashback process completed successfully (LED blinked for ~10 mins then stopped). Result: Even with the freshly flashed BIOS, the system exhibits the exact same failure immediately upon boot.

Note on Physical Condition: During the troubleshooting process (specifically while removing the GPU to isolate the issue after the instability had already rendered the system unusable), the small plastic retention clip on the PCIe slot detached. However, the system's failure persists exactly the same way without any GPU installed (using the onboard iGPU and bare-metal testing), verifying that this is unrelated to the root cause of the failure.

Conclusion: Since the system degraded from a stable state and now fails to output video or power USB devices even after a successful BIOS Flashback (despite a Green Boot LED), I suspect a physical failure of the Motherboard's I/O controller or traces.

Has anyone seen this specific "Green LED but Dead I/O" behavior on the X870 platform? I am preparing to RMA the board but want to be sure I haven't missed anything.

Here's a video of the way it boots.