LG CX annoying signal issue

[beachBOYken]

Hi

I just built my first pc, but I have an odd issue with the signal to my lg cx. Every so often I power on my pc and get no signal on my lg cx.

The only way Ive found to fix is to power off the pc and back on again and it 100% works every time, this to me rules out hdmi cable, as once I have signal I have no signal issues at all, plus I used the hdmi 2.1 certified cable on my series x without issue.

Other things ive tried is disabling "fast start" in power management settings. (I haven't looked in the bios yet perhaps a good idea to disable it there as well)

Ive seen a few threads on the internet with similar issue, some suggest disabling hdmi deep colour, g-sync, but then that disables features I want to use like VRR.

My lg cx is connected to my 4070ti super hdmi port, I have 3 display ports I can try on the gpu also, but unsure if they would support all the features of the hdmi port on the gpu.

My LG CX iidmi port is in PC mode as well.

Also something I notice when I get the no signal on my lg is that the gpu fans are spinning, normally when it boots and I get a signal I find the gpu fans don't spin until I boot into a game.
Also to add it seems to happen so far when I haven't powered on the pc for a while, as in overnight.

 

[Meddling-Monk]

That's a lot of info there, some not necessarily connected.

So the first thing I'd ask is, when you mean no signal on the LG CX, are you saying there's nothing at all being sent to the TV? Or the popup that the PC is connected is not (well) popping up? Or it takes a while before it recognises there is a signal going through via HDMI?

 

[beachBOYken]

That's a lot of info there, some not necessarily connected.

So the first thing I'd ask is, when you mean no signal on the LG CX, are you saying there's nothing at all being sent to the TV? Or the popup that the PC is connected is not (well) popping up? Or it takes a while before it recognises there is a signal going through via HDMI?

As in no signal at all. Im just seeing my LG CX hdmi screen wallpaper.

 

[Meddling-Monk]

OK, and the PC is definitely powered on when you do so? Is it an AMD rig and memory training? (Could take a few minutes on boot then). Just running through early thoughts for now (heading over to my CX and 3060 AMD rig, so can see if I can replicate it once I get enough info).

 

[beachBOYken]

OK, and the PC is definitely powered on when you do so? Is it an AMD rig and memory training? (Could take a few minutes on boot then). Just running through early thoughts for now (heading over to my CX and 3060 AMD rig, so can see if I can replicate it once I get enough info).

Yeah its powered.

I have 7800x3d /nvidia 4070ti super / msi x670e tomahawk/ 64gb corsair vengeance. (expo enabled in bios)

Memory training, isn't that with the very first boot after building?

Its been booting up quickly over the weekend, its just sometimes I get no signal and have to power it down and on again.

Thanks

 

[Meddling-Monk]

Yeah, I have a 7950X and X670E Proart motherboard so somewhat close enough to your setup; sometimes after I boot it up in the morning, it just does the memory training thing all over again. No real reason why either. In those situations, the display obviously won't have a signal as the boot up process hasn't reached the display part yet. Takes a minute or two (or even longer with older BIOS). Just want to make sure that's not what you're seeing first.

And to confirm, when there's no signal, how long did you wait before going for the power down?

 

[beachBOYken]

Yeah, I have a 7950X and X670E Proart motherboard so somewhat close enough to your setup; sometimes after I boot it up in the morning, it just does the memory training thing all over again. No real reason why either. In those situations, the display obviously won't have a signal as the boot up process hasn't reached the display part yet. Takes a minute or two (or even longer with older BIOS). Just want to make sure that's not what you're seeing first.

And to confirm, when there's no signal, how long did you wait before going for the power down?

About 2-3 minutes, maybe longer.

If it happens again which it likely will I will wait longer.

Im going to try disabling fast start in bios though, I heard that can cause these sort of issues.

 

[Meddling-Monk]

I've just tried booting up the newer rig on the CX first then powered on the CX. No issues.
Tried with booting CX first, then PC and no issues.
Tried leaving the CX on the HDMI channel used before shutting it down and booting up a few minutes later, no issues.

Not saying there's no problem, just not replicated it yet.

Oh, in my experience with the CX, I often tune the CX to a digital channel after use before I power it down. As I have found that when you play a game with very low frame rates (something like Command and Conquer at 30fps), if you shut the PC and system down, it sometimes gets stuck and will act funny on being turned back on (VRR enabled). Needed to fully turn it off and unplug to get that one sorted out. So there may be some relation there, but it depends on what you've been doing I guess on the PC.

It might also be there's something off with your 4070 or the HDMI port on it, and that's what's throwing the CX off. Any chance you have another GPU on hand to try out in the interim?

 

[beachBOYken]

I've just tried booting up the newer rig on the CX first then powered on the CX. No issues.
Tried with booting CX first, then PC and no issues.
Tried leaving the CX on the HDMI channel used before shutting it down and booting up a few minutes later, no issues.

Not saying there's no problem, just not replicated it yet.

Oh, in my experience with the CX, I often tune the CX to a digital channel after use before I power it down. As I have found that when you play a game with very low frame rates (something like Command and Conquer at 30fps), if you shut the PC and system down, it sometimes gets stuck and will act funny on being turned back on (VRR enabled). Needed to fully turn it off and unplug to get that one sorted out. So there may be some relation there, but it depends on what you've been doing I guess on the PC.

It might also be there's something off with your 4070 or the HDMI port on it, and that's what's throwing the CX off. Any chance you have another GPU on hand to try out in the interim?

Thanks for testing, no other gpu, I’ve booted again since and no issue, I’ve just entered bios and disabled memory context restore, which is AMDs terminology for “fast boot”. I will see if that helps.

 

[beachBOYken]

@Meddling-Monk

Booted this morning perfectly fine, early days but will see how it goes, there was one thing I noticed that could be a big factor was that my hdmi cable was not all the way in on the pc as the plastic connector was hitting the pc casing, I switched to a smaller profile connector and it looks like it’s fitted better, though it could still be hitting the case ever so slightly might invest in a slimmer profile cable if I can find one.

I also disabled memory context restore in bios that Is known to cause issues, I don’t mind a slightly longer boot time with this setting disabled.

Will see how it goes.