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***ToastyX*** · (Last edited: 11-03-2024, 04:03 PM by ToastyX)

(11-03-2024 04:44 AM)amak Wrote: The monitor doesn't appear in the list of displays...

I don't want to take up too much of your time, but one more thing of note: when I use a DVI cable instead, with a DVI-to-DP adapter, I think a valid EDID does go through, as I can see the monitor name and correct presets in CRU (the only issue there is no analog output to the monitor with that cable/adapter).

Does this narrow this down to a cable/adapter issue, and if so, would a hardware EDID emulator solve the issue?

It could still be the monitor because monitors often have separate EDIDs for each port, so the VGA D-sub port might have a corrupted EDID, while the DVI-A port might not. Since DVI-A is basically just VGA with a different plug, if you happen to have a passive DVI to VGA adapter, you can try DisplayPort to VGA adapter > VGA cable > VGA to DVI-A. If that works, then the EDID is probably corrupted on the monitor's VGA port, which tends to happen to old monitors sometimes when a bit flips in the monitor's EDID EEPROM.

Other options:

1. Use Windows 10, which will allow CRU to work with monitors that don't have a valid EDID.

2. Get a hardware EDID emulator. DisplayPort emulators aren't common and tend to be expensive, but if the adapter passes through the EDID, you can try a cheaper VGA EDID emulator instead. Then you should be able to use CRU with Windows 11. If the emulator is programmable, you could program the EDID directly to the emulator, but programmable ones tend to be more expensive. Edit: A VGA EDID emulator should work if the problem is the monitor or the cable but not if there's an issue with the adapter. A DisplayPort EDID emulator should work for all cases since it comes before the adapter.

3. Fix the EDID on the monitor. The problem is many monitors have the EDID write-protected, although some monitors have a way to disable the write protection through the service menu. I don't know if the IBM C220p is write-protected or if there's a way to disable the write protection. If it's not write-protected, you'll need a video card with a direct VGA connection. Then you can use my EDID/DisplayID Writer if it's an AMD card, or you can use Linux tools such as edid-rw to write the proper EDID.

dotcomma · (Last edited: 11-04-2024, 01:52 PM by dotcomma)

Hello,
I'm trying to set custom max refresh rate on my monitor to be lower than native, but it does not accept it and shows that display resolution is not supported, any idea/tip what can I try please?

My monitor is Samsung OLED G8 with native resolution 3440x1440 at max refresh rate 175 Hz, VRR range is 48-175 (Gsync compatible).
Other than 175Hz, monitor also natively supports 60hz, 100hz and 120Hz resolutions.
I have Nvidia 4080 GPU and using DP connection with DSC, EDID override is accepted and luckily works for me on current Nvidia drivers.

What I tried is to edit Detailed Resolution in DP extension block and change the original 175Hz resolution to 150Hz, but keep the original pixel clock. Unfortunately it does not work, is it possible that VRR monitor is locked to some fixed Max refresh rates? If I try 100 or 120 Hz then it works, but only these. I would expect that if its VRR range is 48-175 it would accept native resolution with any refresh rate withing that range, especially if pixel clock is the same.

The reason for doing this is VRR flicker mitigation where fps limiters don't work.

amak · 11-05-2024, 03:15 AM

(11-03-2024 02:05 PM)ToastyX Wrote:
(11-03-2024 04:44 AM)amak Wrote: The monitor doesn't appear in the list of displays...

I don't want to take up too much of your time, but one more thing of note: when I use a DVI cable instead, with a DVI-to-DP adapter, I think a valid EDID does go through, as I can see the monitor name and correct presets in CRU (the only issue there is no analog output to the monitor with that cable/adapter).

Does this narrow this down to a cable/adapter issue, and if so, would a hardware EDID emulator solve the issue?
It could still be the monitor because monitors often have separate EDIDs for each port, so the VGA D-sub port might have a corrupted EDID, while the DVI-A port might not. Since DVI-A is basically just VGA with a different plug, if you happen to have a passive DVI to VGA adapter, you can try DisplayPort to VGA adapter > VGA cable > VGA to DVI-A. If that works, then the EDID is probably corrupted on the monitor's VGA port, which tends to happen to old monitors sometimes when a bit flips in the monitor's EDID EEPROM.

Other options:

1. Use Windows 10, which will allow CRU to work with monitors that don't have a valid EDID.

2. Get a hardware EDID emulator. DisplayPort emulators aren't common and tend to be expensive, but if the adapter passes through the EDID, you can try a cheaper VGA EDID emulator instead. Then you should be able to use CRU with Windows 11. If the emulator is programmable, you could program the EDID directly to the emulator, but programmable ones tend to be more expensive. Edit: A VGA EDID emulator should work if the problem is the monitor or the cable but not if there's an issue with the adapter. A DisplayPort EDID emulator should work for all cases since it comes before the adapter.

3. Fix the EDID on the monitor. The problem is many monitors have the EDID write-protected, although some monitors have a way to disable the write protection through the service menu. I don't know if the IBM C220p is write-protected or if there's a way to disable the write protection. If it's not write-protected, you'll need a video card with a direct VGA connection. Then you can use my EDID/DisplayID Writer if it's an AMD card, or you can use Linux tools such as edid-rw to write the proper EDID.

Spot on!! Corrupted EDID on the VGA port it seems. A DVI to VGA cable, with the same VGA-to-DP adapter, fixed the EDID issue. The monitor now appears in settings/CRU with the correct name, with all factory display modes filled out in CRU.

I still can't get custom resolutions to appear in settings though :(

Here's the output from both edid-tests we've used (identical), I hope it can pinpoint the issue:

DISPLAY\IBM1A4F\7&176FD83E&0&UID260 (active):
00 FF FF FF FF FF FF 00 24 4D 4F 1A 01 01 01 01
1B 0E 01 03 6E 29 1E AC EB 9C 68 A0 57 4A 9B 26
12 48 4C A4 43 00 D1 59 C1 59 81 99 E1 4F 61 59
45 59 A9 4F 31 59 A6 59 40 30 62 B0 32 40 40 C0
13 00 88 26 11 00 00 1E 00 00 00 FF 00 32 34 2D
42 38 39 32 39 0A 20 20 20 20 00 00 00 FC 00 49
42 4D 20 43 32 32 30 50 20 43 52 54 00 00 00 FD
00 32 A0 1E 82 25 00 0A 20 20 20 20 20 20 00 15

Again, much appreciation for all the help so far.

***ToastyX*** · 11-05-2024, 03:53 PM

(11-05-2024 03:15 AM)amak Wrote: Spot on!! Corrupted EDID on the VGA port it seems. A DVI to VGA cable, with the same VGA-to-DP adapter, fixed the EDID issue. The monitor now appears in settings/CRU with the correct name, with all factory display modes filled out in CRU.

I still can't get custom resolutions to appear in settings though

Here's the output from both edid-tests we've used (identical), I hope it can pinpoint the issue:

Make the changes you want and restart. Then post the edid-test.txt.

***ToastyX*** · 11-05-2024, 03:53 PM

(11-04-2024 01:51 PM)dotcomma Wrote: Hello,
I'm trying to set custom max refresh rate on my monitor to be lower than native, but it does not accept it and shows that display resolution is not supported, any idea/tip what can I try please?

My monitor is Samsung OLED G8 with native resolution 3440x1440 at max refresh rate 175 Hz, VRR range is 48-175 (Gsync compatible).
Other than 175Hz, monitor also natively supports 60hz, 100hz and 120Hz resolutions.
I have Nvidia 4080 GPU and using DP connection with DSC, EDID override is accepted and luckily works for me on current Nvidia drivers.

What I tried is to edit Detailed Resolution in DP extension block and change the original 175Hz resolution to 150Hz, but keep the original pixel clock. Unfortunately it does not work, is it possible that VRR monitor is locked to some fixed Max refresh rates? If I try 100 or 120 Hz then it works, but only these. I would expect that if its VRR range is 48-175 it would accept native resolution with any refresh rate withing that range, especially if pixel clock is the same.

The reason for doing this is VRR flicker mitigation where fps limiters don't work.

What happens with normal timings, not with the same pixel clock? What about 144 Hz?

dotcomma · 11-05-2024, 07:27 PM

(11-05-2024 03:53 PM)ToastyX Wrote:
(11-04-2024 01:51 PM)dotcomma Wrote: Hello,
I'm trying to set custom max refresh rate on my monitor to be lower than native, but it does not accept it and shows that display resolution is not supported, any idea/tip what can I try please?

My monitor is Samsung OLED G8 with native resolution 3440x1440 at max refresh rate 175 Hz, VRR range is 48-175 (Gsync compatible).
Other than 175Hz, monitor also natively supports 60hz, 100hz and 120Hz resolutions.
I have Nvidia 4080 GPU and using DP connection with DSC, EDID override is accepted and luckily works for me on current Nvidia drivers.

What I tried is to edit Detailed Resolution in DP extension block and change the original 175Hz resolution to 150Hz, but keep the original pixel clock. Unfortunately it does not work, is it possible that VRR monitor is locked to some fixed Max refresh rates? If I try 100 or 120 Hz then it works, but only these. I would expect that if its VRR range is 48-175 it would accept native resolution with any refresh rate withing that range, especially if pixel clock is the same.

The reason for doing this is VRR flicker mitigation where fps limiters don't work.
What happens with normal timings, not with the same pixel clock? What about 144 Hz?

Nope, it does not work even with normal timings or 144Hz.

vol.2 · 11-07-2024, 02:34 PM

Quick question. When you wrote about the Alternative Method for Intel GPUs, does the .exe file you export and run effect the monitor itself, or just the PC-side EDID information?

"If you have an older Intel GPU, use the "Export..." button and choose "EXE file" for the file type to export a self-contained EDID override installer. Then run the .exe file and choose "Install EDID" to install the EDID override on all matching displays."

Basically, I'm asking if you meant "for all matching displays," or you actually meant "on all matching displays."

I'm sure this is obvious to most people, but perhaps I don't fully understand how the software works yet. AFAIK, I haven't ever overwritten the EDID information on the monitor itself before.

TIA

***ToastyX*** · 11-07-2024, 03:32 PM

(11-07-2024 02:34 PM)vol.2 Wrote: Quick question. When you wrote about the Alternative Method for Intel GPUs, does the .exe file you export and run effect the monitor itself, or just the PC-side EDID information?

"If you have an older Intel GPU, use the "Export..." button and choose "EXE file" for the file type to export a self-contained EDID override installer. Then run the .exe file and choose "Install EDID" to install the EDID override on all matching displays."

Basically, I'm asking if you meant "for all matching displays," or you actually meant "on all matching displays."

I'm sure this is obvious to most people, but perhaps I don't fully understand how the software works yet. AFAIK, I haven't ever overwritten the EDID information on the monitor itself before.

TIA

CRU doesn't do anything that affects the monitor itself. The alternative method is just an Intel-specific method that's also saved in the registry. It's done separately because I don't have a way to match a specific monitor to a particular output using the Intel-specific method, so it just applies the EDID override to all outputs.

***ToastyX*** · 11-07-2024, 03:34 PM

(11-05-2024 07:27 PM)dotcomma Wrote: Nope, it does not work even with normal timings or 144Hz.

It's possible the monitor only accepts specific refresh rates. What about with HDMI?

dotcomma · (Last edited: 11-08-2024, 06:05 AM by dotcomma)

(11-07-2024 03:34 PM)ToastyX Wrote:
(11-05-2024 07:27 PM)dotcomma Wrote: Nope, it does not work even with normal timings or 144Hz.
It's possible the monitor only accepts specific refresh rates. What about with HDMI?

It has HDMI 2.1, but since it is not possible to raise min VRR range above 48Hz I'm not using it, as I need more than 100Hz min range. Or do you know about some workaround for these HDMI 2.1 limits? Min range cannot go above 48Hz and max range cannot go below 100 if I'm not mistaken.