4600HD Max pixel clock?

[Radius118]

Hi there!

Working on a problem with 4k60 resolution on a machine running i7-4765T with Intel 4600 IGP. A little background:

I have been trying to get full 3840x2160 @ 60 hz resolution out of the display port running at 594MHz pixel clock.

As it is, I can achieve this resolution using the Intel driver custom resolution tab but only using CVT-RB timing which results in a pixel clock of 533MHz.

The issue with that is I am using a device to split my HDMI signal. One signal is full 4K and goes to a 4K display. The other port downscales to 1080p. The problem is this device doesn't handle the non-standard timing of 533MHz properly. It simply passed this signal to the 1080p device which of course does not work.

So, I have been trying to figure out some timing numbers to get the pixel clock up to 594MHz. Nothing seems to work.

I am not sure if I am just not coming up with the right custom timing numbers, or if I am running into a hardware limitation, a BIOS limitation or a driver limitation.

Can anyone help? Thank you!

[ToastyX]

CRU with "Automatic (HDTV)" will give you the timing parameters for 594 MHz:
   

[Radius118]

D'Oh! I didn't even think about using CRU to come up with the timing numbers! Argh.

Thank you for that. I will try it and see what happens

---

Ok so I tried it. No joy. I get the dreaded "the custom resolution exceeds the maximum bandwidth capacity"

Another thing I noticed is that the Intel custom resolution utility seems to be adding a value somewhere.

Taking a look at the screen clip you'll notice that the total on the vertical column does not add up. It is adding a value of 64 somewhere.

If I play around with it and put a generic value of 100 in the back porch, the total is now off by 92. I don't know what is going on with this.

In any case, I reduced the back porch number to 40 to get 594 MHz and I still get the maximum bandwidth capacity error. So now I am fairly sure I am running into a driver limitation, or a hardware/BIOS limitation. I have read of instances were the manufacturers were specifying a maximum CD CLOCK (?) value in BIOS that cannot be changed. Not sure if I am running into that issue here or not.

Thoughts?

[ToastyX]

I don't know what the DisplayPort limit is for 4th generation Intel GPUs, but if it's accepting 533 MHz, then it should support HBR2, which allows up to 720 MHz with 8 bpc color.

What happens if you add the resolution using CRU instead? These drivers should work with CRU:

Windows 10: https://downloadcenter.intel.com/download/30196
Windows 7/8.1: https://downloadcenter.intel.com/download/29970

[Radius118]

(02-06-2021 08:51 PM)ToastyX Wrote:  I don't know what the DisplayPort limit is for 4th generation Intel GPUs, but if it's accepting 533 MHz, then it should support HBR2, which allows up to 720 MHz with 8 bpc color.

What happens if you add the resolution using CRU instead? These drivers should work with CRU:

Windows 10: https://downloadcenter.intel.com/download/30196
Windows 7/8.1: https://downloadcenter.intel.com/download/29970

I don't know. I tried CRU with the driver I am currently running, but I am either not using CRU properly, I don't understand how to use it properly or it won't work with that driver. or a combination of all 3!

I read the instructions on CRU on this forum, but nothing seemed to work. So I don't know what I am doing wrong.

According to the specifications of this machine it shows it should be able to do 3840x2160 @ 60Hz. Which is does. But only at CVT-RB timing. Which is a reduced blanking timing if I understand it correctly. The specs also say something about reduced blanking, so perhaps I am just at the limit of what the hardware/BIOS can do?

I will download and install that driver and try again after I get off work.

Thank you.

[Radius118]

(02-06-2021 08:51 PM)ToastyX Wrote:  I don't know what the DisplayPort limit is for 4th generation Intel GPUs, but if it's accepting 533 MHz, then it should support HBR2, which allows up to 720 MHz with 8 bpc color.

What happens if you add the resolution using CRU instead? These drivers should work with CRU:

Windows 10: https://downloadcenter.intel.com/download/30196
Windows 7/8.1: https://downloadcenter.intel.com/download/29970

Ok so I had some time to try this. I downloaded the driver above and used CRU to add a custom resolution/refresh/timing.

CRU does not seem to be adding the resolution to the registry or I am doing something wrong. I add the resolution, get an asterisk next to my display and click OK. Then I run restart-64 and wait for the driver to restart. Once that happens I go into advanced display settings and the refresh rate I added is not there. The resolution I am trying to add is 3840X2160 at automatic (HDTV) timing. I have also tried Native (HDTV)

I have also noticed that every time I open CRU there is an asterisk by the display name. This seems to indicate that the changes are not being saved? I don't know. I am following the instruction jn the main CRU thread, but it doesn't seem to be working. :/

[ToastyX]

* means the changes were saved. Are you able to add resolutions less than 533 MHz pixel clock?

[Radius118]

(02-15-2021 03:28 AM)ToastyX Wrote:  * means the changes were saved. Are you able to add resolutions less than 533 MHz pixel clock?

Apparently not. I have tried quite a few different configurations, etc. Nothing above 533MHz works. I have the suspicion 533MHz is a limitation of the driver or the hardware. Or both.