1x RTX3090 is absolutely not overkill for gaming however. Nowadays it's barely enough to get 60FPS in 4K in some recently released games. But the shocking part is that my 3090 is still probably worth as much as when I bought it about 4 years ago.
I can’t run 4k HDR cyberpunk 2077 at 240hz with path tracing. I’m managing ~120fps. I’ve got a Blackwell 6000. I didn’t buy it for games, but there are still games and setups where the GPU is the bottleneck. I don’t even have an 8k TV.
There is currently no gpu in production that can max out the largest and fastest displays in graphically demanding games. We have monitors that are the equivalent of two 4k monitors side by side and run at 240hz. I have a 5080 and have to turn down settings to get 60fps in cyberpunk.
That's how most raytracing is done these days anyway. The game is rendered at a much lower resolution, the raytracing math is applied, and then it is upsampled to the target resolution.
If you set the target resolution to 1080p, not much changes in the render pipeline except the that final upscaling step. To get better quality, the lower resolution is bumped up so there is more data to work with for the upsampling, but the scaling performance can be very hit or miss depending on the game as the engine itself often can play a huge role in rendering performance.
As far as rendering the 1080p image at 4k, yea it works fine, but there will always be little artefacts that remain for those looking for them. 1440p seems to be the sweet spot for gamers today, but 4k is really nice for when you're not gaming as most online video is now made for dual use on televisions.
AFAIK nvidia cards dont work in tandem (aka sli in the past) very well these days. So that aint true.
Also, 2 gens old means bad performance at ray tracing, abysmal path tracing if at all. Pretty sure it can't run smoothly CP2077 in native 4k without dlss upscalers with all on ultra.
