What is making you think that?

That means there’s a CPU bottleneck yes. But I’m surprised a 9700k would bottlekneck a 2070 super that severely. It could be configuration issue or throttling or something.

Most of them? What kind of question is this?

Yes but a 2TB HDD isn’t very expensive these days, so you’ll probably be better off just buying another 2TB hard drive than spending nearly as much for a PCB (if you can even source the right one).