Unable to set 3072x1728 @ 30 Hz on 165 MHz cable even with much reduced blanking (UHD 600)

[Real_Phobo]

I have a Celeron-equipped mini PC with UHD 600 graphics running Windows 10.

The mini PC has DP 1.2 outputs, and I have connected it to my monitor using a DP-to-HDMI cable.

Now, the cable is a 165 MHz one. My theory is that it should support any resolution and refresh rate that fits into those 165 MHz, but it doesn't.

I was trying to get 3072x1728 @30 Hz working, using very minimal timings (like 8-16-8 h, 4-8-4 v) but it would never appear in the Display Settings pull-down menu, so it has to be something driver-related.

The maximum I was able to set at an exact 30 Hz that would be accepted by the system was 3008x1728 using CRU and 'Exact' timings. It amounts to 163.80 MHz, so there is 1.2 MHz of bandwith left free.

But something is limiting the horizontal resolution to 3008 because even going minimally higher to 3016 won't work. In that case, 2560x1440 is the highest available resolution (one of the monitor's officially supported), but an additional 2560x1600 will be unlocked, if I manage to set an even higher resolution that will be accepted by the system (like 2880x1620, 2944x1656, 3008x1728, you get the idea).

Can anyone with *proper* knowledge explain to me what causes this limitation?

Real Phobo

[Steven_Intel]

Hello Real_Phobo,

Thank you for posting on the Intel® communities.

I am sorry you are having issues with your Intel graphics. I'll be glad to assist you with that.

To confirm, are you using the Intel Graphics Command Center to select the refresh rate and perform the changes?

In order to better assist you, please perform the following steps:

• Perform a clean installation of the latest graphics drivers available (https://www.intel.com/content/www/us/en/download/19344/intel-graphics-windows-dch-drivers.html).
• If the issue persists, perform a clean installation, but this time with the latest graphics driver provided by the Mini PC manufacturer (if any).
• Make sure Windows 10 is fully updated to the latest version.

If the steps above do not solve the issue, provide the following two reports:

Intel Graphics report: On Windows, look for the Intel® Graphics Command Center > Go to Support > Click on System Diagnostic > Click on Generate report > Save the report as a .txt file and attach it to your reply.

Intel SSU: Download the Intel® SSU https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows- 

Open the application and select "Everything", click on "Scan" to see the system and device information. By default, Intel® SSU will take you to the "Summary View". Click on the menu where it says "Summary" to change to "Detailed View". To save your scan, click on "Next", then "Save". Please attach the file to your reply.

Best regards,

Steven G.

Intel Customer Support Technician.

[Real_Phobo]

Like I wrote, I used CRU for the settings. I also tried the Intel tool, but that one would just give me a "Mode not supported" message without any further explanation. But I need an actual explanation.

Is there some additional limit introduced by the Intel driver when using a cable of this type? Something like a 5 megapixel limit? (But even in the case of such a 5 MP limit, I should still have to be able to set 3016 or 3024 horizontally.)

Or are there any specific minimum values for blanking? (But values out of range would trigger the "Bad parameters" message, so that wouldn't make sense, either. )

Or does the driver listen for some specific bandwidth limits, like multiples of 10 MHz? (But that wouldn't explain why I've been able to set lower resolutions or lower refresh rates with a bandwidth above 160 MHz.)

[Steven_Intel]

Many thanks for your reply.

In order for us to investigate about what could be happening and answer your questions, we need you to perform the steps recommended on the previous post and provide the requested reports, as that would help us to isolate the issue.

Look forward to hearing back from you.

Best regards,

Steven G.

Intel Customer Support Technician.

[Real_Phobo]

I have made the issue pretty clear, you do not need any further info from me. Instead, you need to get some info from your driver developers because they are the ones responsible for the imposed limitations.

It would be great to know what the driver actually does there.

[Steven_Intel]

Many thanks for your response.

We usually request this information as it would help us to get to a resolution as fast as possible, however, we understand you do not want to provide that information.

I am going to keep working on this based on the information we currently have. As soon as I have an update on this matter, I will let you know.

Best regards,

Steven G.

Intel Customer Support Technician.

[Real_Phobo]

Thank you Steven, this is much appreciated.

BTW, I should have mentioned that the cable is capable of transmitting a standard 4K resolution (3840x2160) at 30 Hz when the audio channels get disabled.

However, this does not seem possible with the Intel driver as there is no way to disable the display audio; it does work with Microsoft's Basic Display Adapter driver, though, as that one doesn't provide DP/HDMI audio.

Best regards,

Real Phobo

[Steven_Intel]

Hello Real_Phobo,

After reviewing this issue, we concluded that we still need additional information from you in order to investigate further.

We would need the following information:

Intel® System Support Utility (Intel® SSU) report: Download the Intel® SSU https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows- 

Open the application and select "Everything", click on "Scan" to see the system and device information. By default, Intel® SSU will take you to the "Summary View". Click on the menu where it says "Summary" to change to "Detailed View". To save your scan, click on "Next", then "Save". Please attach the file to your reply.

Intel Graphics Command Center report with the monitor connected (using a straight connection, since adapters or converters are not supported, as this could vary the way EDID is read by the driver): On Windows, look for the Intel® Graphics Command Center > Go to Support > Click on System Diagnostic > Click on Generate report > Save the report as a .txt file and attach it to your reply.

If you are willing to provide this information, please post it on your next reply, and we will be happy to continue with the assistance.

Best regards,

Steven G.

Intel Customer Support Technician.

[Steven_Intel]

We would like to know if you were able to check the previous post.

Let us know if you still need assistance.

Best regards,

Steven G.

Intel Customer Support Technician.

[Real_Phobo]

Hi Steven,

Yes, I saw it. Here's the two files.

The SSU report was done with the adapter cable connected, the IGCC report was done with a DP 1.4 cable connected. Both the PC and monitor support DP 1.2, so there were no issues.

The described issue arises from the adapter cable which for some reason related to bandwidth and DP/HDMI audio cannot go beyond 3008x1728 @ 30 Hz even if that is less than its 165 MHz limitation would suggest.

Best regards,

Real Phobo

[Steven_Intel]

Many thanks for the information provided.

Just wanted to let you know that we are currently working on this on our end. As soon as I have an update, I will let you know.

Best regards,

Steven G.

Intel Customer Support Technician.

[Steven_Intel]

Hello Real_Phobo,

Many thanks for your patience on this matter.

After working on this issue and based on the steps performed, we have determined that the issue is related to the display configuration. Our best recommendation is to contact the monitor manufacturer for more information and/or get further assistance.

Please keep in mind that this thread will no longer be monitored by Intel. Thank you for your understanding.  

Best regards,

Steven G.

Intel Customer Support Technician.