Problems with 4K screens in 60 Hz and SST – SweClockers investigates

It is spring for a new generation of screens with the resolution 4K UHD. One of the biggest news is the 60 Hz refresh rate over single-stream transport (SST), which eliminates the need for the problematic technology multi-stream transport (MST). In short, the change means that the entire screen image is sent in a single stream instead of being divided and “glued together” afterwards.

However, the new screens mean an increased flow of error reports. For SweClockers, the member “Hymer” draws attention to the fact that many users have problems, especially with AMD’s graphics cards in combination with new 4K screens for 60 Hz SST. The symptoms are flashing image or no signal at all, both with a single graphics card and in Crossfire.

SweClockers examines in the test lab

To investigate the phenomenon, the editors are loading the test rig with the AMD Radeon R9 290X and the new monitor Samsung U28D590D. Very true, already after a few seconds the image starts to jump and then turns into a black screen.

However, the solution turns out to be simpler than expected. A quick change to the Displayport cable included in Samsung’s box provides a perfect 60 Hz image over SST, without any graphical artifacts. When the cable is replaced with another from the editorial office’s hiding place, the problems return immediately.

Further tests show that of the five available cables of different sections, only Samsung’s included variant works in 60 Hz SST with AMD Radeon R9 290X. Interestingly, all cables with Geforce GTX 780 Ti work in the same situation. All five can also be used for 60 Hz over MST with a different screen, a technology that in practice requires the same bandwidth.

Exactly what the problems are due to is difficult to dial into. One theory is that the electronics in the first generation 60 Hz screens with SST are extra sensitive, which together with weaker signal from AMD cards requires Samsung’s apparently more expensive cable. The majority of tested cables are admittedly marked Displayport 1.2, but below the surface there may be other compromises.

Last but not least, even if a cable change works wonders for SweClocker’s test rig, the same does not have to apply to everyone. There may be more factors that affect 60 Hz and SST, but which do not appear to the editors. It is also worth mentioning that some users also report problems with Nvidia cards, something that is not noticed during SweClocker’s tests.

Footnote: Samsung Displayport cable has article number BN39-01879A. Of the remaining variants, two come from Deltaco, one from Bizlink and the last cable from a monitor from Dell. All are 1.5 to 2.0 meters long.