It's been a long time since I started the post.
Anyhow I was able to exchange the rtx to 1070Ti! I have installed mac OS High Sierra! But I'm facing few problems.
1. My motherboard Asus ROG STRIX Z390E comes with wifi, I'm unable to use WiFi
2. the nvidia drivers are not installed(used nvidia web drivers), the screen flickers in the login screen and in about this mac i see graphics as "Unknown 256mb"
3. RAM that I'm using is 16GB 3200MHz, what I'm seeing is 16GB 2133MHz
any idea what might be the problem...!