GFX upgrade or new system?

[gotoPzero]

My current gaming PC is from 2016. Spec as follows

i7 6700k
32gb ram
1070ti
2 x 1440 monitors.

I am starting to see it struggle a bit and would like to get back into sim racing a bit more this winter.

Would something like a 3070ti give me enough of a boost or is the CPU the limiting factor?

I would like to get another few years out of it but if its the CPU then I think I am looking at a new system basically.

[gotoPzero]

Cheers chaps makes sense I guess to get a new GPU first then.

Already running the system on an M.2 and a couple of Samsung SSDs for the games.

So 3070ti or something else? Budget is c.£300 ish lets say?