4k Monitor Lag via Display port

[KoD Krysco 51]

Ive had twin Samsung U28D590D 28" 4k UHD monitors and recently came across a lag issue. Until recently, I ran one monitor on Display port and one on HDMI (old card only had one display port). I upgraded my PC to a MSI GTX 980ti Gaming 6G and now run display port cables to each monitor.

I noticed this mainly with Netflix but if I watch Netflix on the left monitor, its perfect, but if I watch it on the right monitor, its pretty laggy. The left monitor has a 6ft display port cable that came with the monitor. The right side one has a 15ft display port cable from Amazon as it has to be that long with the way I have things setup. I tried swapping cables and it reverses the issue making it clear that the 15ft cable is the culprit.

My original question was, is 15ft too long for a display port cable powering a 4k monitor? I then think it changed when I realized that everything works great besides netflix. The Netflix stream certainly isnt 4k, but the monitor resolution is. ONLY Netflix lags on the 15ft cable. I can play The Witcher 3 fine in 4k Ultra and ive also watched the same youtube video on both monitors at the same time. They run identically with no lag. How can only Netflix be effected by the 15ft cable?

I also tried the 3rd, unused display port spot on the 980ti and its no different. Its 100% the cable.

** Since its Netflix that is my problem, let me edit this by saying that my internet is great, I have a 50Mbps download and a 5Mbps upload.

 

[boju]

Displayport cable's maximum length is in theory 5 meters so being 15ft roughly 4.5m should be fine, long as the cable is certified by Displayport and carries their logo.

 

[boju]

Have a look here; http://www.displayport.org/cables/how-to-choose-a-displayport-cable-and-not-get-a-bad-one/

 

[bigpinkdragon286]

Certified or not, you need to consider the gauge of the conductors inside the cable. If the card you're using is putting out a low grade or marginal signal over the Displayport, you may have to go with a cable that has higher gauge conductors inside. Also, if you're routing the cable near anything that can induce noise, you could be causing additional signal loss.