It’s hardware dependent, so nothing you can do about it.
Then try to disable deinterlace in “Video settings” when you start a video as shown in the screenshot. This option is also hardware dependent, so it might also not be available in your system:
Nice workaround you got there! N2/+ will be a fine beast along. About the noise from HDD, you could try to get an internal SSD (good price per GB) in an enclosure from Orico or Sabrent.
Deinterlace method is greyed out and listed as ‘off’. It appears that 20.1ne offers no way to modify whatever deinterlacing it’s doing on a 905X4. That’s partly why I’d like to know if those with other hardware see the same temp rises on interlaced material.
I think that if you disable “Hardware acceleration” in Settings/Player/Videos that Deinterlace options will become available. Then you can check the temperatures with different deinterlace options.
But using software decoding will definitely rise the temperatures of the device. I use deinterlacing with my live tv material and the temperature of any device stays low. It only rises with SW decoding in some inpustream adaptive stream addons.
Of course that temperature will rise; but only the difference between different settings is of interest…
Yes, that worked. With Hardware Accel off the Video Settings menu now gives me the options Off, Half and Deinterlace. If I select Off, stop the video and restart it the info page now says deinterlace method unknown (and Off is still selected in Video Settings) but … Kodi is still still producing a 1080p59.94 stream, as reported by both the info page and by the TV. It looks like there’s no way to get it to stop deinterlacing on this hardware. And of course with hardware h264 decoding off the temp just ramps up even faster.
I’ll have to be honest, I’m not really that bothered about 1080i performance. If someone were to argue that 1080i should have gone and died in a ditch ten years ago they wouldn’t get any disagreement from me. But it is something that people will encounter from time to time. After drilling some holes in the top of my new 905X4 box I was feeling quite happy seeing it do long stints of 4k HDR material while staying in the mid-50s and just happened to try a BR rip I had sitting on my NAS, which gave me a shock.
Since 1080i is still a widely spread broadcasting format (more than half satelite channels use it) it will stay around for indefinite time 
I did a similar thermal mod on my Tanix X4 as I had on my X96 Air in July 2020 I think.
Details:-
The CPU is underneath the PCB, with a miserable attempt to provide a heatsink, and very poor airflow, which all combined caused my device to reach 75°C while playing HD content. It might have been trottling at that but I did not check.
The work:-
I cut a 20x20mm of 3.5mm thick material from an old heatsink and placed that on top of the CPU.
I then used the existing heat plate on top of that piece, making sure to avoid touching any other component.
I used on top of those, a heatsink from my scrap box which had a springsteel clamp built-in. Heatsink size is 56x48mm, and is proud of the case by ~23mm.
The whole assembly resulted in the sprinsteel clamps protuding just above the box edges.
I cut a suitable sized and positioned hole in the bottom cover, and slipped it over the heatsink, pressing down against the springsteel clamp legs until the cover snapped into place.
The cover clips are strong enough to keep pressure on the heatsink so everything is kept in place.
Of course I applied thermal grease between all those parts to ensure thermal connectivity. When next I get to it I intend to use thermal glue for some of the thermal connections.
The result is impressive … the temperature of the CPU maxed out at 49°C playing the same content.
It is presently idling at 39°C. Ambient is ~23°C.
This is what it looks like after I flipped the digits of the clock using Openvfd. I have yet to put some small feet on what was once the top which will now be the bottom.
