Question / Help Sound & picture asynchron after few hours of OBS work

I'd be extremely grateful for advice:

Recently I were to offer streaming service from studio camera for my client. I have external webpresenter blackmagic catching card, communicating with streaming dedicated computer with USB, with no extra drivers needed (mounted as usual webcamera). Web presenter captures signal from EX3 Sony studio camera within the loop, via SDI interface, resolution 720x1280/50fps and transfers it to streaming dedicated computer of following specification:

Imac 27-inch 2012
2,9 ghz Intel i-5
8GB ram
Nvidia geforce gtx 512 MB
disc 500 SSD

The computer has its own separate internet connection with 25MB upload. For streaming to YT I have used OBS, setting bitrage at 2900 with 6 seconds cache, codec x264, resolution unchanged and frame rate of 29,7, key frames interval - 4 and procesor load - ultrafast. Everything works fine for some time. After 5 hours of work, rapidly occurs asynchron of sound with picture of 0,5 sec - which is about 15 frames. In the next session even after 1 hour the same problem occur. Fast restart of OBS and streaming helps (fortunately performed during one session on YT). What is interesting - OBS statistics for the lost render frames, encoder and stream are at 0 level.

Could it be caused by OBS wrong settings? Webpresenter is blackmagic new product, selling like hot cakes, and there are no drivers, which could have errors/ cause problems. Following the webpresenter, the camera connects furtherly with line editing in adobe premiere computer, where no drops occure even after all day of working.
 
Top