[EDIT]hmmm.....whats going on at AMD? (and history of 3Dfx Rampage)

[BoFox]

http://www.techpowerup.com/reviews/AMD/R...re/21.html

At just $398, about the same price as the cheapest GeForce GTX 1070 you can find, or $478 for a pair of 8 GB cards like we have, the Radeon RX 480 CrossFire is not a viable solution, if you plan to buy two cards upfront. When averaged over all our games it is consistently slower than a single GeForce GTX 1070 at all the resolutions that matter - 1080p, 1440p, and 4K. Instead of buying two cards upfront, you're much better off putting your monies into a single GTX 1070, not just for better performance but also to dodge the spectre of application multi-GPU support, which continues to haunt both SLI and CrossFire.

We averaged games that do take advantage of CrossFire in a separate relative performance data-point than the overall relative-performance. The findings are interesting, when averaged among games that do scale, the RX 480 CrossFire is about 5-10% faster than a GTX 1070. However, only 6 out of 16 tests are taking advantage of the second card.
.....

Some of the latest DirectX 11 games (eg: Just Case 3) and the early DirectX 12 ones, are struggling with multi-GPU support. NVIDIA too, has cut out 3-way and 4-way SLI support (but for slightly different reasons), making us wonder if it's worth the trouble following a multi-GPU upgrade path with mid-thru-performance segment cards such as the RX 480. We rather recommend you spend $398-458 on a single GPU solution.

OUCH!  6 out of 16!!!  It's never been that bad since AMD first started doing Crossfire with the X850XT cards, I think.  Even the generation after that when I had SLI cards, I never went back to a multi-GPU configuration because it's just not worth it.  I noticed microstuttering way before review sites ever started talking about it (where 40 fps felt like 22 fps for example). 

Then there's this horrible hitching in GTAV with all AMD cards, not just with Crossfire but with single GPUs:



Is AMD ever going to fix this hitch-fest, for one of the by far most popular games ever? 

One artifact that these charts don’t entirely capture is an intermittent stutter suffered by AMD’s cards. Big frame time spikes on the Radeon R9 390 are our only data-based indicator of this, but every card exhibits the behavior.
...
This time the spikes are observable on the 480, 390X and 290, though they appear to be outliers when, in reality, they’re far more persistent.

http://www.tomshardware.com/reviews/amd-...616-5.html

I'd gladly lose 40% of the frame rate just to see the game-breaking hitching go away, but thankfully we have Nvidia.

If AMD's the 2nd-best GPU designer in the world, with brilliant engineers, they could definitely resolve the hitching, but I think they deliberately left that there just to maintain 10-15% higher frame rate for benchmarks.  And, hardly any vocal AMD fanboy really wants to complain about it, while NV fans don't bother with AMD cards to even care.