So I’ve got a living room computer running Cachy OS/Plasma Bigscreen that has replaced my Xbox. (I’m calling it the Xbox None)

It’s an old Dell Optiplex I picked up for cheap - runs indie titles pretty well and I can stream from my main PC.

Anyway, that’s not why I’m posting..

I can’t seem to find a way to get it to turn the TV on and off when it goes to sleep and wake up. Can anyone help?

Edit: thanks for the answers! I don’t want to buy an adapter so I guess I’ll live with having to use the remote. 🤷‍♂️ I am going to see if the TV settings can help me out though.

It is rare that a computer have HDMI-CEC natively.
Try the command "cec-ctl" (which is part of v4l-utils) or take a look at the Arch Wiki.

Even if your hardware doesn't support it, you can still use displayport with an adapter or even a usb+hdmi adapter.

I'm pretty sure it's a hardware feature of specific graphic cards. Not every HDMI port has that capability and most consumer GPUs don't have it. That's why the GPU on the Steam machine is so important. It has the CEC capability out of the box.

I have a similar setup to you, but I'm running bazzite. I got around it by putting my TV (offline Hisense Roku) into a power saving mode that essentially shuts the screen off and puts it in standby. Whenever there's a change in signal, the display kicks on. However that also isn't a feature on every TV.

I think you can buy an adapter

You'll need a Pulse8 USB CEC adapter.

Ahh, this is a good idea. It’s an LG smart TV :/ (inherited from my late mother 🤷‍♂️)

I think it can do that.. I’ll have to muck around.

Ohhhh, I do have a display port and a display port to HDMI adapter already. Would this work or would the TV need display port too?

I don’t want to buy more stuff :(

Would this work for an older receiver that doesn't have CEC natively?

The TV will be connected with HDMI and computer will have its DisplayPort converted to HDMI by a supported adapter. But:

most adapters do not support the CEC Tunneling feature, and of those that do many did not actually connect the CEC pin. Unfortunately, this means that while a CEC device is created, it is actually all alone in the world and will never be able to see other CEC devices.

DisplayPort to HDMI Adapters with working CEC

HDMI-CEC Tunneling over DisplayPort | Arch Wiki

TL;DR

Connect your computer's DisplayPort with DP-HDMI adapter to TV's HDMI. To test if the adapter tunnels CEC, run in a terminal:

cec-ctl --playback && cec-ctl -S

Which should show at least two devices.

No, the TV has to support HDMI-CEC in order for the computer to power it on and off. If it does not, then perhaps an IR adapter to simulate a remote?

Thanks for the answer. I appreciate it. My TV does support CEC but doesn't work for power on/power off.

Thanks! I’ll give it a shot!