Neither have been released yet. Wait for them to be released and real world benchmark results available.

Both 1070 and 1080 support directx 12_1 same as the previous generation Nvidia cards.

Both cards have been advertised as faster than a titan X, with the 1080 approximately 20-30% faster. You could check the metaverse benchmarks for Titan X results as a point of reference.

Already I made the request in my usual supplier of the faster 1080 when available this month just dont know yet if i will wait for the 1080 ti .

1.  GTX 1080 is utilising a GP104-400 GPU manufactured using the 16nm FinFET fabrication process.

2.  8GB GDDRX memory, a 2500MHz memory clock (10GHz effective) and a 256-bit memory interface, providing total memory bandwidth of 320 GB/s.

3.  GTX 1080  bether then Titan X or 2 sli 980 and we still dont know full details.

Will be lot fun put my 980TI strix and the 1080 together..

Just has i always say ,its your choice but Nvidea or AMD both great buys.

yes and for the most, the best is wait to compare this 2 industries cards.

For me i always have buy NV stuff and was always happy with it, so since in a win team we showldnt change i will keep, but i know that AMD have great surprises this year with Polaris as an architecture that will deliver a “historic” leap in performance per watt.

Read more: http://wccftech.com/amd-greenland-gpu-hbm2-14nm-2016/#ixzz485nPgoOD )

What bugs me is that, near the end of 2015, nVidia basically acknowledged that their GPUs/drivers (emphasis on drivers) weren't as well designed/developed for DX12 as AMDs. A lot of this discussion was about asynchronous compute but has widened a bit since. There is at least one post to that effect on this forum. And they implied that there would be something driver-based to help. This hasn't materialized and it's May.

Now the big hype over the 10-series GPUs. I'm absolutely certain they'll out-perform the 9-series line, including the Titans. But has the design of the chip come to further embrace the direction of DX12 and, more specifically, multiple-GPU (I'll call it MGPU) configurations? From what (admittedly small amount) of reading I've done about the presentation and products, nothing has been stated about this concern of mine. That tells me AMD's hardware/driver combination still holds a better design for DX12 and MGPU, but it's not as refined and shrunk down as nVidia's getting their 10-series.

I'm a huge nVidia fanboy. Every AMD product I've ever had died an early death or didn't work out of the box. And it's now been years since I owned a product of theirs. But I'd really like to be on the winning team with this tech as it's the future - as I see it - for gaming performance, including MGPU. And if nVidia's continuing down a path simply shrinking and speeding up what they have in the 9-series cards then I would submit that's not the best direction to go.

The next big release for AMD will beat out the 10-series, sure. We see these two GPU giants trade top spots with each new tech release. But nVidia's had a lead in production tech aiding their leads for years. If they're going down the wrong tech path AMD will continue to gain over the years.

The 1070 will be a cheaper 980Ti with slight upgrades for under $400. That's why you're seeing used 980Ti's popping up for well under $500. Those asking prices will continue to drop in coming weeks. The 1080 smacks down the Titans and the R9 Furies. I want to jump on this tech bandwagon as badly as anyone. But I need more information about how they're embracing DX12's capabilities and their design/driver issues when compared to AMD's latest tech. Just shrinking dies, adding a few core, and overclocking further doesn't seem like a winning direction for where I want to go.

Just my $.02 from my (perhaps limited) perspective.

There is a lot of buzz right now about the 1080s that are in the benchmark database. I've skimmed some of that. Again, the 1080 will be king when released. But to me it's about more than that.

nVidia's design is great for DX11. It's DX12 where it's either an unsound design or the drivers don't enable well, or a bit of both. And so far nVidia won't seemingly disclose their position.

I contacted a tech writer I have faith in on just this issue this morning. It appears there is more information about the 10-series that hasn't yet been released. Perhaps I'll have better answers by the end of this month.

Don't expect AMD's next release to beat the 10 series.  Unless they're hiding stuff, they're aiming to replace the 390 this summer, but not the Fury cards.  In which case they'll probably have good DX12 performance, but they may not even beat the 980ti since that would mean they were as fast or faster than the Fury X, let alone the 1080.  If they do surprise us with an enthusiast replacement for the Fury X, then the 1080 has good odds of being dethroned big time, at least in DX12, but a 390X isn't anywhere near a 980 Ti in performance, it's just really good value wise.

There are rumors going around that custom non-ref version of 1080 from AIBs could clock up to 2,4GHz... if true, the cards could actually be quite awesome. I was bit disappointed by the low CUDA core count, but if they can clock that high, the performance could get perhaps 40 percent above OCed 980Ti, which is quite acceptable. All in all, i am fairly glad i skipped 980Ti last year, should be getting better GPU now for more or less the same money, and not better just by some miniscule difference (like in 980 vs 780Ti case, now that was waste of money). 

Without drivers that have been optimized for the 10-series, I might add.

Oh, agreed. And that relates to my point, above. But I imagine that the drivers that will be available when the 1080s are released will exceed the 10-12% performance improvement.

A bit more choice :

https://www.bluesnews.com/s/171643/nvidia-gtx-1080-review-roundup 

The AMD Radeon R9 Fury X has just 4 - 8 Frames per Second less at Ashes of the Singularity, but cost the half of a GTX 1080! It seems NVidia improves their asynch. computing but is not better there than AMD by a doubled Price. The question is, how important is async. comp. for the next two years at the gaming industry?

Oh, look! The Ashes benchmark site has Nvidia GTX 1080 results in it. I wonder when that happened?

Ohh Anandtech are on there. Looking at their 1440p Extreme benchmark history it appears they run the same test several times, as a good professional site should. Well, they should then average them out and hopefully not cherry pick the one they want for whatever reason Though I have found the benchmark to be pretty consistent.