Can I just change my GPU from GTX 960 to 970 on a working 10.13.1 build?

So my question is basically if I turn off power, swap GPUs and would it work? If not, what would I need to change?

Also I'm still tossing up between a free 970 from a friend or a 1070 Ti from fb marketplace so could be either but I suppose the procedures would be the same? Please correct me if I'm wrong. Thanks in advance!

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Specs:

i5-4670

Gigabyte GA-Z87M-D3HP

Running 10.13.1 with Clover and one of WebDriver-378.10.10.10.20.107-109. Apologies I can't remember exactly which GPU driver is currently being installed as this was built a couple years ago.