I bought this PC 5 years ago, today it struggles a bit on some games that require a lot of CPU. The graphics card is doing pretty well.
I'd like to update it, starting with the CPU, and switch to AMD, for better compatibility with Linux and notably to be able to encode videos more easily, I often edit long +4K videos.
Do you have any advice? The aim would be not to change my motherboard. And for the new components to last 5 years too? You can also advise me on graphics cards.
Like others said you pretty much have to change the motherboard for a decent upgrade. The next question is whether you upgrade to DDR5 or not. Which I think DDR4 would still be good enough in 5 years period.
You can't switch to AMD without getting a new motherboard (either AM4 or AM5 socket).
If you choose to salvage as much HW as possible, then you can go for AM4 motherboard (B550 chipset for instance) along with some R7 5700X, then you can reuse pretty much everything else (probably cpu cooler too) else. Although I'd prefer to have at least 3200MHz ram sticks for Ryzen.
I really don't know if your video encoding is more stressful on your cpu or gpu, but generally AMD gpus work better for linux than nVidia ones do.
So let's say I switch to AM5 sockets, I would need to change the RAM (say 32GB 6000MHz ~100 EUR) and a new (better) AMD CPU, which one? I'd like the RAM + CPU + motherboard change not to exceed 550 EUR. Would the graphics card still be compatible? Would upgrading the CPU be worth it at that price?
You could replace the CPU with R7 7700 but that's maybe 100€ on top of that.
Regarding GPU, yes it still would be compatible and you could still replace that down the road with something more powerful, maybe when next generation of GPUs will arrive, I don't know what resolution you're running but 2070S is still relevant graphics card.
Considering CPU uplift, it seems to be more or less double the performance - link to benchmarks.
Motherboard has to be changed no matter you are upgrading to the latest Intel or moving to AMD. CPU-wise I dun think AMD is significantly more compatible with Linux than Intel... You may have confused the situation regarding GPU.
AM4 is on its last leg. So if you really make a change to AMD, I suggest moving to AM5 which means you need to drop your RAM too as AM5 only supports DDR5.
Since money is a concern, look at buying AM4 with a higher priced B550 motherboard, 5800x3D processor, for RAM look at 3600Mhz, you can keep everything else.
That patform is end of life but will be a real jump in performance, more cores and more cache. You could then upgrade in 2 years to an X770 board, DDR5 will be much lower priced, and AM5 will be a lot more ironed out with better graphics built into processors.