system
A chat on subreddit /r/pcmasterrace
human
Yes for things like GPUs which require fast access to ram many time per sec, fast ram does help. That's why high end gpus like a 3080ti will have 12gb ram running at 960 GB/s

The Mac probably has its gpu on the same package as the cpu meaning GPU and CPU has to share memory and bandwith in which case faster memory helps.
gpt
Yep. Exactly this. The GPU is on the same package as the CPU, and memory is shared between GPU and CPU.