http://techreport.com/review/28513/amd-radeon-r9-fury-x-graphics-card-reviewed

Nvidia Geforce GTX 980Ti wins in

Project Cars

Witcher 3

GTA V

Alien Isolation

Civilization: Beyond Earth

Battlefield 4

Crysis 3

AMD Radeon R9 Fury X wins in

Far Cry 3

All games tested at 4K

It's significantly behind in lower resolutions. Around 5+% across the board at 1440p. It's a bit weaker than I expected but that's how it goes.

What's actually really bad is that it's apparently really hard to overclock despite being watercooled. The testers I frequent couldn't bring it above 1115MHz (base 1050MHz) without getting artifacts. While the 980ti is base clocked at 1000MHZ and has partner cards with custom coolers that go beyond 1400MHz.

I'm really interested to see how well the partner cards can manage it. That the stock models are close together means nothing if the partner cards are far apart. In these price regions partner cards are the only thing that matters.

Partner cards are not allowed to be overclocked

"You can expect this distinctive layout from all Fury X cards, because AMD has imposed tight controls for this product. Board makers won't be free to tweak clock speeds or to supply custom cooling for the Fury X."

http://techreport.com/review/28513/amd-radeon-r9-fury-x-graphics-card-reviewed/2

Makes me wonder how bad the air cooled Fury will be cut down with how strict AMD are being with the Fury X

Fury has the edge, the higher the resolution goes. The 4GB are not a limiting factor there. But that is more due to Nvidia performing bad at higher resolutions rather than AMD performing well.
The lower the resolution, the better Nvidia performs against AMD cards. That has been the case for several generations now.

At the review site I trust the Fury wins in almost every 4k game, some 1440p games and only one 1080p game.

However that doesn't count for a lot since it lags behind in almost every game against an overclocket 980ti.

Well Hexus.net (http://hexus.net/tech/reviews/graphics/84170-amd-radeon-r9-fury-x-4gb/) tests 8 games

 The GTX 980 Ti wins in every game at 1080P and all but Tomb raider and Shadow of Morder at 1440P.

Arstechnica mentions out of 4 sites that have Fury X benchmarks Toms is an outlier in performance and one reason why I never use them is that I can get the same results as most sites but Toms is always different.

Well we better hope TSMC can get there 16nm fabs running or we won't get new GPU's till 2017.

The results vary a little from site to site, but they show the same pattern: 980Ti is better in 1080 and 1440p, period. In 4K the situation is not so clear and Fury X wins in some games, but not by much.

Overall, if anyone is in the market for a high end card, the 980Ti is their best option unless cooling or physical space are a problem.

Fury X and 980 Ti are 1440p cards, 4K@60fps is not achievable with them in modern titles at highest settings. I usually pay most attention to Guru3D and Anandtech's benchmarks, latter is not up yet, but here is Guru's:

http://www.guru3d.com/articles_pages/amd_radeon_r9_fury_x_review,1.html