8K video was automatically transcoded to 1080p in NVENCC,it crashes in FFMPEG Version

[Selur]

Did you try it with NVENCC HW decoder?

Doesn't help since my 8k source was a ProRes file which the VPU can't decode.
(In general the hardware decoder works fine.)

Satelit and TV proivider companies have big bulky special industrial HW encoders, with laughable meemory size,...

I doubt that. 8k HEVC will require quite a bit of RAM, especially if you use 4:4:4 and a large lookahead, there's not really a way around that.
(even H.264 4k hardware encoder like the VEGA 3300-series should have quite a bit of memory,..)

[Selur]

https://github.com/rigaya/NVEnc/issues/127
-> seems like 8k 4:4:4 10bit simply isn't meant to be 8 GB cards
(4k 4:4:4 10bit and 8K 10bit 4:2:0 both work fine)

[Selur]

in case you don't monitor the NVEncC issue tracker I linked to above:
With the new NVEncC 4.42 8k 4:4:4 10bit encoding is possible (but terribly slow) on 8GB cards when using '--lookahed 0'.

Cu Selur