I was thinking about upgrading my 1080 to a 1080ti, but honeslty I don't think it'll be worth it, even if you're running a 1070. If you're running a 1070 and can sell it and buy a used 1080 for a decent price, that would be worth it. But best I could sell my 1080 in my area is for $450, and cheapest 1080ti i have been able to find is for $650 used which is not worth it at all for me especially with such a new architecture so close around the corner. To put into perspective, I did buy a 1070 in january, and sold it for $425 in like july, bought a 1080 for $450. But ain't gonna sell for $450 and buy for $650....