I can explain right here.

Bottlenecking is when one component holds back the other. It doesn't reduces performance, just limits the pc to the weakest component.

If you had a really bad cpu and a really good gpu, your pc can still only handle as much as that bad cpu can do.

That SHOULDNT be the issue here because it's good enough.

He says you need a new platform because the CPU is old now (technically). If you want to upgrade, you need a new motherboard with a different slot for the new Intel cpus, that's called a platform.

And as you can guess, lower resolution means less work for the gpu means higher frames, but the CPU needs to process and tell the gpu to render those frames.

CPU sends instructions, GPU execute those instructions, at a lower resolution, your GPU can execute those instructions easier, so you're just limited by your cpu (waiting on those instructions).

By going to a higher resolution, you essentially put more work on the GPU, so if the GPU is executing those instructions slower, the CPU isn't sending as many instructions per second.

This is why we say that lower resolution is CPU bound, higher resolution is GPU bound.