quadro k4200 width Watchout, why low fps

Hi, I’m working with media server Dataton Watchout
And I use the Quadro k4200 videocard

In the specifications it is indicated that the card can work with 4 displays (using Mst)
Or 3 displays (2 DP + 1 DVI).

When I connect 3 displays, the maximum resolution I get is only 720p each. In this case, if I run 3 videos in 1080p, the computer starts to lag a lot.

After I took another such card and unified it in the SLI, but did not notice an increase in performance.

Is this normal behavior for this graphics card or am I having problems?

my pc:
Intel Core i7
asus x99-a
ddr-3 16gb
ssd

Thank you

The card is definitely capable of decoding 3 1080p videos simultaneously. It is very likely to be a problem with the application used to decode and display the videos, which may not be optimized for such a use-case.