4k@60Hz + SST possible with HD 5500?

[JHaas2]

Hi,

I'm using a Thinkpad x250 together with an ASUS PB287Q 4k display that uses SST mode through an Ultrabase dockingstation. Unfortunately I can only select 30Hz max for 4k resolution. The display is connected by DP. I already enabled DisplayPort 1.2 in the monitor settings and installed latest Intel reference drivers.

Is it even possible to achieve 60Hz with an SST and a HD 5500? Will there be an updated driver in the future that will support 4k@60Hz & SST?

[Silvia_L_Intel1]

Hello Katmai, thanks for joining the Intel Community.

According to the following link, the HD5500 support the following resolution https://software.intel.com/en-us/articles/quick-reference-guide-to-intel-processor-graphics https://software.intel.com/en-us/articles/quick-reference-guide-to-intel-processor-graphics

If you are not getting 4k@60Hz, please check with Thinkpad if they support that resolution.

In addition, you can send me the dxdiag report? (Start -> Run -> dxdiag -> Save All Information).

[JHaas2]

Hi Sylvia,

Thank you for your reply. I know that the HD5500 ought to support 4k@60Hz. I am not very confident it does so with every 4k monitor currently available, as there are two different methods to stream the picture (MST and SST) and there seems to be an issue with the SST method.

My question is: will SST ever be supported by the HD5500?

The Thinkpad officially supports that resolution & frequency, but is also unspecific about the transport method.

[ROBERT_U_Intel]

Hi Katmai

HD5500 (Broadwell) graphics does support 4K@60 in general. Setting this mode requires at least 540MHz core display clock (CDCLK) to drive a ~536MHz dot clock. If the OEM (Lenovo in this case) does not support 540MHz or higher CDCLK in the system BIOS, the system will not be able to drive 4K@60 over SST, only over MST (tiled display).

I would recommend contacting Lenovo to verify their support for SST and 540MHz CDCLK.

Thanks

Robert

[BKaca]

For the ThinkPad series, you have usually a bios setting showing the how display port should be used, on the dock, physical display port etc. I believe there are 4 settings, so if you connect directly from the X250 to the 4k60Hz supporting monitor you need to select Digital Display (physical port available on X250) and F10/save quit. I would recommend using the latest BIOS available through Lenovo website as well. Quick installation, no need to burn cd or usb. Hope this helps.