SupraGSX wrote on 2025-12-04, 05:58:

Fixed with following method. […]
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Fixed with following method.

The root cause is the EDID modern monitors expose, which XP interprets incorrectly.
Fixing the EDID so XP detects HDMI-HDTV enables Nvidia’s HDMI audio device.

This method is tested on an Alienware AW3423DW, but should apply to any modern display that's recognized as DVI

1. Ensure UAA HD Audio Driver Is Installed (Required for Audio Enumeration)

Windows XP SP3 does not include a working UAA HD Audio driver.
The original KB888111 patch only installs on SP2.

You need the patched SP3 version so XP can enumerate HD Audio devices such as:

HDAUDIO\FUNC_01&VEN_10DE (Nvidia HDMI audio)

Once installed, confirm the bus driver:

C:\Windows\System32\drivers\hdaudbus.sys

If UAA is not installed, HDMI audio will never appear — regardless of EDID fixes.

2. Install Nvidia Display Driver and Nvidia HD Audio Driver (Any Known Working Method)

You must have:

A functioning display driver (e.g., 355.98)

A functioning Nvidia HD Audio driver (e.g., from 344.11)

This guide assumes the user already knows how to install these manually through Device Manager.

At this stage, the Nvidia HD Audio driver can be installed but XP still won't let you select it as playback device.

3. The Real Problem: XP Thinks Your HDMI Display is DVI

4. Solution: Override the EDID With a Correct HDMI + Audio Version

You must provide XP with an EDID override that includes:

A valid CEA Extension Block

HDMI capability flag

Audio Data Block (LPCM 2ch @ 32/44/48 kHz)

No HDR metadata

A native timing XP/Nvidia can handle

There are two ways to create this EDID:

Phoenix EDID Designer

Edit the existing EDID
– Add CEA block
– Add HDMI bits
– Add audio
– Remove HDR
– Set native timing
Export as .bin

Create a monitor INF (required for Windows XP)

XP cannot load .bin EDIDs directly.
You must embed the EDID inside a monitor driver INF.

The INF supplies:

HKR,"EDID_OVERRIDE",...
HKR,,VideoInterfaceType=2 ; Forces HDMI

Once installed, XP prefers this EDID over the physical EDID.

5. Install the EDID Override INF in Windows XP

1. Device Manager → Monitors

2. Right-click your monitor → Update Driver

3. “Install from a list or specific location”

4. “Don’t search. I will choose”

5. Have Disk…

6. Browse to your EDID override INF

7. Install → reboot

After reboot, XP should show the connector as: HDMI-HDTV and audio should be working.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e96e-e325-11ce-bfc1-08002be10318}\

Can you dump this reg key to a file?
I'm moderately sure, somewhere in there, the EDID things you did will show up.

In which case, it can probably be made generic, one click reg, inf, or bat.