4k recording pc screen broken up

[oldboilermaker]

I am using a Blackmagic Intensity 4k pro to record the extended display on my pc at 2160p.
The OBS preview shows a broken up display and flickering (see attached screen shots).

The 4k displays works fine if I view it directly on my 4K monitor. The Blackmagic card seems to be detecting the 2160p/30hz resolution, it just does not display properly. It does not work at all with Blackmagic Media Express set to 2160p/30hz. No other frequencies work either.

If I go to 1080p everything works fine.

System info:
NVIDIA GeForce GTX1060 6gb driver 32.0.15.7680 dated 06/12/2025
AsRock Z390 motherboard
Intel i9/9900 processor
16gb memory
multiple SSDs for recording
Blackmagic driver 14.5.0.0 dated 01/28/2025
Windows 11

 

[oldboilermaker]

oops: forgot 16gb mainboard memory

 

[oldboilermaker]

obs version 31.0.4

 

[rockbottom]

Is 8-bit BGRA the default Pixel Format? Is NV12 available? The only BMD piece I have is the MP4 encoder & that is a standalone thing/discontinued.
HDMI 1.4 cables can be fussy with 4k/60, all are not created equally. I upgraded everything in my 4k workflow to HDMI 2.1 spec a few years ago. Apparently 2.2 is now available.