I settled on the 980ti in the end after having the Fury X for a few days. The 980ti is so much better.
The Fury X was ok, but I seemed to have nothing but problems with it. Performance was erratic, drivers caused problems with my PC hanging, etc etc. Was told to update the bios but checked that and it wasn't the problem as they were already uptodate. In the end I was glad to see the back of it.
Going back to Nvidia was like a breath of fresh air, and the performance of the 980ti is second to none. An outstanding card.
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Edit: Just wanted to add, the best I got out of the amd fury x was 2.0ss in med/high but that was just supercruising around with no NPC's or players as I was 50k out. Hit a roid field and I'd have to switch down to 1.5 SS and lower settings. With SweetFX on, 1.5 was a major struggle too.
The 980ti is in a different league. Flying around in a roid field with 2.0 SS in game, and most things on high, including shadows, and it's super smooth and solid. My card is somewhat overclocked though.
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Edit: Just wanted to add - The 980ti is a MASSIVE card. I think mine was 280mm and it only just about fit in to my case (antec 900) with a few adjustments to the drive bays.