4K/UHD resolution on Haswell: HBR2 via DP supported?

[CWind]

Hi,

we are testing Haswell systems with new 28" UHD-resolution Display Samsung U28D590D.

This monitor has DP1.2 and HDMI 1.4a inputs.

As expected, 3840x2160@30Hz works via HDMI on Haswell platforms.

Unfortunately, via DisplayPort, no 4K resolution works with this display.

Via DP, Haswell until now only seems to be able to use Multi-Stream Transport (MST) to display 3840x2160@60Hz.

With Single Stream (SST), only 3840x2160@30Hz seems to be possible.

The Samsung U28D590D seems to expect High Bitrate 2 mode with 5.4 GT/s via DP (HBR2).

According to datasheets, Haswell (4th gen Core i) does support HBR2. But is it really usable?

Driver is 15.33.18.64.3496 on Windows 8.1 x64

Christof

[Allan_J_Intel1]

Thanks for coming back to the community.

I understand you need information about Display Port supporting 4K resolutions.

I have found some specifications of the Display Port and screen resolutions. Please take a look at the below information:

Thanks

Allan.

[SStei10]

Support of 3840x2160@60Hz without MST mode is limited to a select few Haswell models though (Haswell-H). The data sheets for the others say 3840x2160@30Hz, but are technically capable of driving 3840x2160@60Hz in tiled mode (using DisplayPort 1.2's MST feature). Reviews of current 4K screens say there's no GFX card actually driving a 4K display at 60Hz without MST. MST does require appropriate driver support and I've yet to find an official statement stating that intel officially supports that (a few months back there was a stucky up that said such support was under consideration), yet Asus has a video up that tells you you can use intel's collage mode to driver their tiled mode 4K display (tiled mode meaning the display acts like two 1920x2160 screens... so it's two displays, thus requiring Displayport MST and hence requiring driver support to make the whole thing appear as one screen).

[Allan_J_Intel1]

Thanks for the information. I am currently researching on this issue. As soon as I can, I will send you a message with my findings. Thank you for your patience and understanding.

Allan.

[SStei10]

Interestingly, it seems the Samsung screen is single tile. However, that means you could be running into the limitation of most Haswell chips. Except for the H series, they are not rated for doing 3840x2160@60, only at 30Hz (at least that's according to the data sheets). So for instance the U models used in Ultrabooks, can only work in tiled mode.

[SStei10]

I read that the upcoming Broadwell U and Y models should drive those single tiled beasts.. but for now.. marketing is not being entirely truthful with their boasting about 4K capabilities full capabilities only apply to a subset of all Haswell CPUs.

[Allan_J_Intel1]

Thank you for your patience, I am still checking with engineering about this matter. As soon as I get more details, I will come back here.

Allan.

[Allan_J_Intel1]

Were you able to address 3840x2160@30Hz issue?

As I mentioned on one of the post, with a 4th generation processor you could get 3840x2160@60H.

Allan.

[SStei10]

I only have a tiled 4K screen - so somebody with a non tiled model would have to say whether the latest drivers change anything. As far as I gather from the datasheet, the non -H Haswell models won't handle those displays. But they support the tiled screens just fine, if the necessary drivers are installed.

Or can you get a non tiled 4K display working on an Haswell U processor? If the silicone doesn't support HBR2, I doubt that will ever work before replacing the CPU with a Broadwell model.

[EJone5]

allan_intel,

It has been (5) months, we are waiting for your answer to which Intel processors for desktop has a 540Mhz CDCLK rate for the valid processor support of 4K (3840x2160@60Hz) mode using DP/1.2 set to SST or a configuration that will achieve the 4K (3840x2160@60Hz) on a UHD television. As I state above to robert_u, I can acheive WQHD 2560x1440@60Hz as the best resolution.

I feel Intel should be able to provide a rapid and simple explanation/instruction to create results in the real world of 4K (3840x2160@60Hz) on DP 1.2. We need enjoy the 4K resolution at 60Hz that we were promised and paid for.

We are choosing this route DP 1.2 (3840x2160@60Hz) because HDMI 2.0 at 3804x2160 only provides 30Hz bandwidth capacity at the best. 30Hz at 4K is just plain useless for action subject matter like a sports event or movie.

We await a response, please.

[ROBERT_U_Intel]

@ veryconfused

DP does support what you are asking. Have you verified the issue with the latest graphics driver here: https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24348&lang=eng&ProdId=3719 Intel® Download Center

Thanks

Robert

[dcart1]

Hi,

Just want to clarify that 3840x2160@60Hz is supported by the desktop models. "when people say it's limited to "a select few Haswell models though (Haswell-H)" I think they are specifically referring to mobile processors.

[ROBERT_U_Intel]

All,,

The main requirement for supporting 4K@60 on DP SST (single-stream transport) is that the core display clock (CDCLK), which is configured by SBIOS, must be set high enough to drive the dot clock required by the mode. Usually 4K@60 has a 536MHz dot clock, so it requires a 540MHz CDCLK. If the system OEM did not configure the CDCLK at 540MHz for thermal, power saving, or other reasons, then the system will not be able to drive 4K@60 over a single DP stream. Also, Haswell ULT (-U) and ULX (-Y) are limited to 450MHz and 337MHz CDCLK, so they will not be able to do 4K@60 SST. ULT should still be able to do 4K@60 MST, though. ULX can't because 4K MST still requires HBR2.

This shouldn't affect DP MST tiled displays because for those we use two streams, each for one half of the display, reducing the pixel clock.

Additionally, 4K support is only available on the Core processor graphics. Celeron and Pentium do not support 4K. All Core Haswell processors will support HBR2 with the exception of Haswell ULX.

Here is a reference guide that can be of help.

https://software.intel.com/en-us/articles/quick-reference-guide-to-intel-processor-graphics Quick Reference Guide to 4th Generation Intel® Core™ Processor Graphics (formerly codenamed Haswell) | Intel® Developer …

Excerpt from above:

Processor4th generation Intel® Core™ processor family (Intel® Iris™ Pro Graphics 5200 / Intel® Iris™ Graphics 5100, Intel® HD Graphics 5000 / 4600 / 4400 / 4200)3rd generation Intel® Core™ processor family (Intel® HD Graphics 4000 / 2500)

FEATURE

BENEFIT

Maximum Display Resolution

Higher pixel resolutions allow the PC to show more image detail.

DisplayPort* 1.2 / eDP*

H-Processors: 3840 x 2160@60Hz (Ultra-HD) U-Processors: 3200 x 2000 @60 Hz, 3840x2160@30Hz Y-Processors: 2560 x 1600 @ 60 Hz HDMI* 4096 x 2304, 3840x2160 @ 24Hz / 24bpp DVI 1920 x 1200 @ 60Hz

[FBert1]

Hi,

I want to connect two 4k 60Hz displays to my T440p with its docking station. I'm using a Haswell 4800MQ with CDCLK 540MHz. Does this mean that the Haswell GPU generally supports more than one display in 4k 60Hz mode using SST?

[JEFFREY_F_Intel]

@Burtan-

There are couple possible answers to your question:

1) If your system has 2 DP1.2 output ports (say a desktop had 2 DP1.2 physical ports on the mother board) or laptop/dock interface includes two DP1.2 links), and and each link drives separate SST monitor (or one driving SST and one driving MST), the answer would be "yes, should work". This is because HD 4600 (and Iris 5200) support HBR2 on DP (540Mpix/sec) link rate AND pixel clock per pipe of (540MPix/sec) - 3840x2160*60Hz = 498MPix/sec. It will, of course, depend on whether the dock itself has enough bandwidth and has 2 DP1.2 outputs. Note that DVI and HDMI connectors can't drive mailto:4k@60 4k@60.

2) if your system has ONE DP output port (e.g. either physical output OR through the laptop/dock interface) and you connect 2 DP monitors daisy chained or connected via DP hub, then the answer is NO. The link between the 1 DP out on your system and the DP In on the hub is limited by the max link rate (540MPix/sec).... trying to send 2 mailto:4k@60 4k@60 SST streams over that link = 996MPix/sec.

3) Some modern Lenovo systems use USB3.0-based docs and use DisplayLink over USB to send the video signal from the PC to the dock. Not sure how well that works for high res displays... likely not well.

[EJone5]

Your findings are really spot on. They are very useful.

I took my i5-4690K processor on a H97 motherboard to Best Buy to plug a DP 1.2 cable, from the PC, to a Panasonic AX800U 4K TV. I adjusted the DP settings on the AX800U to SST.

I achieved on WQHD 2560x1440@60HZ. I was so close to 3840x2160@60Hz.

What kind of 5th generation processor for a desktop, will allow me to achieve 3840x2160@60Hz?

[JEFFREY_F_Intel]

@veryconfused

The HD4600 in the system you have should be able to drive mailto:4k@60Hz 4k@60Hz over DP1.2 for either SST or MST monitors. We have tested this in house with a number of 4K displays and confirmed mailto:4k@60 4k@60 was achieved with both SST and MST monitors.

The only things I can think of why you are maxed out at mailto:25x16@60 25x16@60. Can you provide info on the specifics of which display you are testing with? is it the same 4K Panasonic AX800U mentioned above that you tried at Best Buy? Can you get mailto:4k@60 4k@60 with MST enabled?

[DSamu1]

Thanks very much for your answer... It has taken me three solid google sessions to get here. My problem is that I can't get my Surface Pro 3 (i5 4300U/8GB RAM) to output 4k @ 60Hz on my Samsung U28D590D display.

So I gather that my problem is that because the Samsung monitor is a Single Tile Display, the Surface Pro 3 (due to the CDCLK limit of 450Mz) will not be able to output 4k @ 60Hz on this monitor. So, since all Surface Pro 3 Models (including the i7 model) used Haswell U series chips, I have to return my monitor and actually get one with a multi-tile display and output using MST instead. Is this correct?

Also as a workaround, could I purchase a mini Displayport to HDMI cable to force the Samsung monitor to display at 30Hz, and then be able to output at 4k?

[JEFFREY_F_Intel]

sorry - didn't see your reply for long time. Yes, the limitation is present on all 15W and lower skus with HD 4200 and HD 44000 graphics - shouldn't make any difference between Core i5 vs Core i7.

MST monitor should work for you.

Alternatively, on SST monitor, as you suggested you could use DP->HDMI to get 4K 30Hz (assuming monitor supports 4k@30 and has HDMI in). You may also be able to simply select 4K@30 with DP cable?