There have been various standards of hdmi cables available on the market but the typical cable available today is under the high speed hdmi certification.
Displayport cable lengths.
Therefore an hdmi to displayport cable will be stuck at 15 for its maximum length.
What is the recommended length of a displayport.
Keep in mind however that multiple connections can weaken the signal so daisy chaining extensions may result in a shorter practical maximum length.
A standard displayport cable including the so call displayport 1 1 cables will work for any displayport configuration including the new capabilities enabled by displayport 1 2 including 4k and multi stream capabilities.
For example a standalone hdmi cable can go up to 65 while a standard displayport cable can go up to 15.
Ymmv with cheaper cables.
Displayport cables up to 50ft.
35 ft displayport cable with latches m m.
I ll add that these are the highest quality most expensive cables i could find.
This decision limited confusion in the market place but set the maximum limit for a certified displayport cable at 5 metres.
Panel mount displayport extension cable.
When using cables with two different ends the distance limit will be subject to whichever type of connector has the shorter maximum distance.
Active cables are specifically designed to exceed the suggested maximum lengths and are tested at the listed specifications for example the maximum listed resolution.
Now i m using one 2 meters cable and two 3 meters cables with two active displayport extenders between them to drive a 2560x1440 monitor at 165hz.
All standard displayport cables support rbr hbr high bit rate and hbr2 high bit rate 2 which can support 4k at 60hz.
The displayport standard does not specify any maximum length for cables though the displayport 1 2 standard does set a minimum requirement that all cables up to 2 meters in length must support hbr2 speeds 21 6 gbit s and all cables of any length must support rbr speeds 6 48 gbit s.
Displayport can be extended with a passive cable up to its maximum spec length.
Unfortunately as is often the case with low cost consumer appliances not all high speed hdmi cables can actually deliver the proper quality.