Display Port Adaptor Question

[Shahmatt]

My motherboard only has a functional Display Port. I connect a DP monitor to this output.

I want to also connect a TV HDMI port to the motherboard using a switch. The idea is to switch between the DP monitor and HDMI TV using the switch. I don't need outputs on both TV and monitor at the same time.

I already had a Bi-directional DP-in to Two DP-out switch. I also had a DP to HDMI adaptor.

So I did the following connection:

Motherboard DP cable connected to Bi-directional DP switch
One output of DP switch connects to DP display (this works)
Second output of DP switch to DP to HDMI adaptor, which is in turn connected to HDMI cable to HDMI TV. (this does not work)

The problem is that I don't get an HDMI signal on the TV.

I tried the following checks:
1. Connected second output to DP monitor using the HDMI port instead. This does not work either. So confirmed it is not a TV HDMI port problem.
2. Connected motherboard directly to DP to HDMI adaptor + HDMI cable to monitor into the HDMI port. This works. So introduction of Bi-directional switch breaks the connection.
3. Switched outputs on the Bi-directional switch. No difference.

I'm guessing this is not working because of some problem with the adaptor or switch.

Is there any way to try to solve this, e.g if I use a DP to HDMI cable, instead of adaptor + HDMI cable, will it work?

Appreciate any advice,

 

[soreloser]

i just chatgpted it:

ChatGPT said:​

This setup won't work the way the user intends because of how DisplayPort to HDMI conversion and switches work. Let me explain:

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Why it fails:​

1. The DP-to-HDMI adapter is not passive
   • Most DP-to-HDMI adapters are active (contain circuitry to convert DP signals to HDMI).
   • A DP switch is designed to switch native DP signals only.
   • When you try to put a DP-to-HDMI adapter after the switch, the switch is passing a raw DP signal through — and the adapter likely doesn't get the right voltage, handshake, or power to do the conversion properly.
2. DP switches are finicky with signal conversion
   • Bi-directional DP switches often don't pass auxiliary power or DDC signals reliably, which are needed for adapters or for EDID handshake with the display.
   • This is why the direct DP → adapter → HDMI TV setup works, but adding the switch in between breaks it.

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Common misconceptions:​

“Will a DP-to-HDMI cable work instead of adapter + HDMI cable?”

No, it will not fix the issue. Those cables just integrate the adapter into the cable head. They still require the same signal compatibility, and your switch will still block it.

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Working alternatives:​

To get this working correctly, the user should consider:

Option 1: Use a DisplayPort MST Hub (if motherboard supports it)​

• This splits a DP signal into multiple independent displays (some hubs offer HDMI outputs).
• Check if their motherboard/iGPU supports DisplayPort MST (Multi-Stream Transport).
• This works for extending or duplicating desktop to multiple displays.

Option 2: Use a DisplayPort KVM switch that supports DP-to-HDMI conversion​

• Some advanced KVM/AV switches explicitly support mixed outputs like DP to HDMI.
• Example: Club3D or Cable Matters make DisplayPort switches with active HDMI conversion built in.

Option 3: Use a dedicated HDMI output from the GPU or motherboard​

• If possible, just use the motherboard HDMI out or install a GPU with HDMI.
• Most motherboards have both HDMI and DP; if not, a USB-C to HDMI adapter (if USB-C supports DisplayPort Alt Mode) may be a workaround.

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Summary​

The issue is not the HDMI cable, nor the adapter — it's that DP switches can't carry or power the signal conversion needed for HDMI. To solve this:

• Avoid mixing signal types (DP to HDMI) through passive switches.
• Use an active hub or adapter before switching, or better, use proper outputs for each display.

Let me know if you want specific product suggestions or diagrams.

 

[Shahmatt]

Thanks for your help

 

[deepblue_82]

i think u can buy a cheap hub that can switch between displays