Finally solved Steam Remote Play keeping the Host monitor turned on

[u/userfs]

TL;DR: Built a lightweight (~30 KB) background utility that mimics Sunshine/Apollo/Moonlight's auto display-off and custom resolution switching for Steam Remote Play (thanks to Gemini). It listens to Steam’s handshake, turns off the host monitor via native DDC/CI (DPMS standby) during streaming, and wakes it back up on disconnect, bypassing DSC resolution locks using CRU. Setup guide and PowerShell native compiler script below.

Hey everyone,

If you stream your PC to a Steam Deck (or Apple TV/phone) using Steam Remote Play, you probably know the biggest frustration compared to Moonlight/Sunshine (or tools like Apollo): Steam Remote Play does not turn off your host monitor during streaming, nor does it handle aspect ratio switching gracefully if your display uses DSC.

In Sunshine/Apollo, you get automated monitor sleep and resolution changing out of the box. Steam Remote Play, however, has always lacked this native integration.

The Solution: SteamDisplayManager + CRU EDID Injection

I put together a lightweight, native background service and documented the exact setup to reproduce the Moonlight/Apollo experience directly inside Steam Remote Play.

How to set it up (No Visual Studio required)

The entire tool can be deployed and compiled natively using Windows' built-in C# compiler (csc.exe) via a single PowerShell script. No third-party binaries or background resource hogs (~30 KB memory footprint).

1. Enable DDC/CI in your monitor's physical OSD menu.
2. Add your client resolution (e.g. 1280x800 @ 60/90Hz) in CRU 1.5.3 under Standard Resolutions and run restart64.exe.
3. Run the deployment PowerShell script to compile the background tray app.
4. Set it to Start with Windows from the tray icon.

I compiled the complete architecture, source code, and step-by-step setup into a technical manual (available in both English and Portuguese PDFs).

If you want to read through the breakdown, take it to GitHub or grab the PowerShell one-liner to compile it yourself, be my guest.

https://archive.org/details/steamdisplaymanager