Davinci Resolve + Rx 5700 Tx

[VVK]

Hi. I changed a graphic card recently to Radeon RX 5700 TX Nitro+ and started learning Davinci Resolve ('coz Premier ignores this new card and Vegas output quality is not so good).
First tests were in 1080p and I was really excited, everything works fine and fast. But then I tried 4k... (see the link). Timeline and project settings match with final export settings. It happens with h264 / h265, QuickTime DNxHD is fine.
Is that hardware issues or am I doing something wrong?

Asus Z87A, i7-4770k, I know it's old, but still works.

https://www.dropbox.com/s/qehv5d1eve945eb/Untitled.mp4?dl=0

[ChapmanDolly]

H264 & h265 require a lot of CPU processing especially at 4k. One thing to try is reducing the render speed. Try setting it at 25 or lower and see what happens.

[Attachment 51786 - Click to enlarge]

[VVK]

Thanks for your reply. It will take some time to try that, 2 hours after I created this post my MB gone to heaven
Building a new system now.