NV_Modes Persistence Tool

Auto-restores custom resolutions on Samsung Odyssey OLED G9 (and other DSC-locked monitors) after every NVIDIA driver update. Set it once, forget about it.

Install

1. Get the files. Clone or download this repo to a stable location — Task Scheduler stores absolute paths, so don't leave it in Downloads.

git clone https://github.com/izu-x/OdysseyG9NvidiaCustomResolutions.git C:\Tools\NvModes
cd C:\Tools\NvModes

2. Configure NVIDIA Control Panel — one-time. Without this, custom resolutions either won't appear, will run at reduced refresh, or will lose Adaptive Sync.

Adjust desktop size and position → select the G9:

• Select a scaling mode: Aspect ratio
• Perform scaling on: GPU
• ✅ Override the scaling mode set by games and programs
• Apply

The GPU upscales the custom resolution to fill the panel height while preserving aspect ratio (black bars on the sides only). The monitor still receives a native 5120×1440 @ 240 Hz signal, so DSC stays happy.

If Aspect ratio causes VRR/G-Sync issues at custom resolutions, switch to No scaling (sends the timing as-is, panel centers a smaller image with borders on all sides).

3. Add your resolutions and install the scheduled task. Open PowerShell as Administrator:

Set-ExecutionPolicy -Scope Process Bypass

.\Set-NvModes.ps1 -Add 2304x1440      # add as many as you want
.\Set-NvModes.ps1 -Install            # registers SYSTEM scheduled task

Reboot. Done — the resolutions appear in NVIDIA Control Panel and survive every driver update.

Managing resolutions

.\Set-NvModes.ps1 -Add 3440x1440      # append + apply
.\Set-NvModes.ps1 -Remove 2304x1440   # remove + apply
.\Set-NvModes.ps1 -List               # show live NV_Modes + configured customs
.\Set-NvModes.ps1                     # interactive menu (list/add/remove/etc.)

The tool stores customs in custom-resolutions.txt (gitignored). One entry per line:

# WxH (default mask 1FFF)
2304x1440

# Or explicit mask
2560x1440x8,16,32,64=1FFF

Why

DSC-locked monitors at 240 Hz (G9 OLED — G93SC / G93SD / G95SC, Neo G9, similar) hit a wall:

• CRU's custom resolutions never appear in NVIDIA Control Panel.
• NVCP's Customize… button is greyed out.
• The only working path is editing NV_Modes in the registry.
• Every driver update wipes it.

This tool automates the persistence and gives you a clean CLI so you never hand-edit a 1000-character registry string.

How it works

NV_Modes is a registry string the NVIDIA driver reads at init. Adding entries forces NVCP to expose extra resolutions even when EDID/DisplayID doesn't.

The catch: the value lives at a path like

HKLM\SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000

The \0000 suffix is not stable — it shifts to \0001, \0002, etc. after a DDU run, GPU swap, or Windows feature update. Static .reg files break silently when this happens.

The script:

1. Walks every subkey under the display class and filters by DriverDesc matching your NVIDIA GPU.
2. Reads the live NV_Modes, strips entries listed in custom-resolutions.txt, re-appends them, writes back.
3. Skips the write if the value is already current (Task Scheduler-safe — no backup spam).
4. Auto-exports a .reg backup before every change. Keeps the last 20.

-Install registers a SYSTEM-level scheduled task that runs -Apply on system startup, workstation unlock, and Display event ID 1 (driver re-init).

Reference

Command	Action
.\Set-NvModes.ps1	Interactive menu
.\Set-NvModes.ps1 -List	Show live NV_Modes + configured customs
.\Set-NvModes.ps1 -Add WxH	Append resolution and apply
.\Set-NvModes.ps1 -Remove WxH	Drop resolution and apply
.\Set-NvModes.ps1 -Apply	Re-write NV_Modes from config (idempotent)
.\Set-NvModes.ps1 -Backup	Export current NV_Modes to backups\*.reg
.\Set-NvModes.ps1 -Restore <file>	Restore from a backup
.\Set-NvModes.ps1 -Install	Register scheduled task
.\Set-NvModes.ps1 -Uninstall	Remove scheduled task

Parameter	Default	Purpose
-GpuMatch	*NVIDIA*	DriverDesc wildcard. Narrow with *RTX 4090* for multi-GPU
-ConfigPath	.\custom-resolutions.txt	Custom resolutions file
-BackupDir	.\backups	Where .reg exports go
-KeepBackups	20	Max backups retained
-TaskName	NV_Modes Persistence	Scheduled task name

Uninstall

.\Set-NvModes.ps1 -Uninstall
.\Set-NvModes.ps1 -Restore .\backups\<earliest>.reg

Then reboot.

Prior art

• u/SpaghettiDuders — original Reddit workaround documenting the NV_Modes + NVCP scaling combo.
• JoshKeegan/OdysseyG9NvidiaResolutionFix — Go CLI for the original VA Neo G9. Predates the OLED line, requires manual re-run after driver updates.
• ToastyX — diagnosis of the underlying CRU / DisplayID 2.0 / DSC limitation, and CRU itself.

Disclaimer

Modifies the Windows registry under the display adapter class. Reversible — the script auto-backs up before each write; restore via -Restore. Not affiliated with NVIDIA, Samsung, or ToastyX.

License

MIT — do whatever, no warranty.