braking of video during capture in and out

Hello, I till now I got next mac (2007 year or earlier) conf: 2*6 core xeon 12Gb ram, SSD, capture in: Active silicon PHX-D10HDSDI, video out: NVIDIA GTX285 2Gb vram;
Mac OS 10.6.8 cat software 4.40m364

conf of signal:
sdi in-> video out-> datapathx4 ->:
1) dvi/optical transmitter -> matrix kramer ->big lcd wall 1920*1080
2) dvi/optical transmitter -> tvone-> matrix kramer -> small lcd wall 1920*720
3) dvi/optical transmitter -> tvone-> matrix snell -> lcd monitor 1920*1080
4) preview monitor 1920*1080

overall 3840*2160*25hz

So there is a problem:
I receive SDI from Nexio Media Server, type of video is movie title. So when I start to send it to big lcd wall after 30-60 seconds its start to break for 0,5-1,5 sec like problem with a buffering. When playing from mac directly haven't a problem. When playing from nexio color movie haven't problem. Just only problem with a move black-white title. When this title playing directly from nexio to big lcd wall haven't any problem. Catalyst saying that FPS on capture in is prefect w/o any drops.

So may be some 1 know device that can check buffer on video cards or ay be some1 know what to check and method?