Surface 8 wont detect 3rd screen

Hi Jim,

Thanks for sharing all the steps you’ve already tried  it’s clear you’ve put in a lot of effort, and I know how frustrating it can be when things still aren’t working after all that. Let’s see if we can get that third screen up and running together.

Here’s what we can check next:

1Dock & Monitor Compatibility

Your Surface Pro 8 can handle two external displays natively. If you’re going for a third, make sure:

Your dock supports DisplayLink or Thunderbolt 4  these are key for multi-monitor setups.

If you’re using DisplayPort daisy-chaining, your monitors need to support MST (Multi-Stream Transport).

Cable Quality Matters

Use high-quality cables like HDMI 2.0, DisplayPort 1.2+, or Thunderbolt 4.

Keep them under 6 feet to avoid signal issues.

If you’re using USB-C, double-check that the cable supports video output, not just charging.

 Clear Out Old Display Settings

Sometimes Windows holds onto old display configs. Try this:

Unplug your Surface from the dock.

Run the official Surface Dock registry fix from Microsoft.

Restart your Surface and reconnect the dock.

Update Dock Firmware

Use the Surface app to check for dock firmware updates, or grab them manually:

Surface Dock 2 Firmware

Surface Thunderbolt 4 Dock Firmware

 Force Windows to Detect the Display

Hit Win + P and choose Extend or Duplicate.

Then go to Settings → System → Display → Multiple Displays → Detect.

Try a Direct Connection

Plug the third monitor directly into your Surface using USB-C or HDMI. If it works, the dock might be the bottleneck.

Let me know if you want help checking your dock’s specs or walking through any of these steps. We’ll get this sorted  no stress!