I'm not perfectly happy with the performance of my 1080ti (Asus ROG-STRIX-GTX1080TI-11G) in 4K as it can't constantly push 60 Frames in some newer games. I bought the card in August last year and it has been moderatly used (didn't get to play a lot the first half of this year due to personal reasons), I would say on average 3-4 hours a week, if that. No overclocking or fuddling around with it, temps in gaming never exceeding 75°C, no mining or cloud computing or other unusual loads. So, I figure it's in pretty pristine shape.
If someone in Europe is interested in that card for about 600EUR + shipping, I might fancy the step up to a 2080ti and get rid of my sub-60 frames. Let me know if you are interested, one disclaimer though: Once we agree on the deal it will take me about one week or ten days to order and swap in the new card, before I can ship the old one out. I'm not in a particular hurry so if you are looking for a card urgently there might be better sellers
I've been a member here on the site since forever and sold/bought a few items from ICE, so I think my reputation is somewhere in the "Good Trader Thread".