I want to buy this card but franky the story behind this board is fuzzy. I mean their claim is loud and clear «19 GPU» but in reality you can have 13 conventional GPU and 6 mining ones. Could you please give me clear answers to the following questions that everyone needs to hear? 
I still don't understand if I can mix AMD and Nvidia cards respectively on Windows / Linux. I want my GPU to be 100% GTX 1070 but this question could become crucial later on[/li]
[li]We all know that the issue is caused by Asus itself but I don't get if this is a clear bug or a wanted "feature"[/li]
[li]Asus promised a BIOS update (maybe) aimed to solve this bug (or feature?). What's the hell is going on? Their latest update doesn't change anything[/li]
[li]Final question: buy or pass? If we pass what is its closest alternative?[/li][/list]
I still don't understand if I can mix AMD and Nvidia cards respectively on Windows / Linux. I want my GPU to be 100% GTX 1070 but this question could become crucial later on[/li]
[li]We all know that the issue is caused by Asus itself but I don't get if this is a clear bug or a wanted "feature"[/li]
[li]Asus promised a BIOS update (maybe) aimed to solve this bug (or feature?). What's the hell is going on? Their latest update doesn't change anything[/li]
[li]Final question: buy or pass? If we pass what is its closest alternative?[/li][/list]
You can mix AMD and NVidia on Windows easily, at a cost in stability.
The jury is out but indicating "not" on recent LINUX version - the NVidia drivers and the AMD drivers USED to be able to coexist but that capability seems to have been dropped by NVidia around drivers version 361.
It MIGHT still be possible via workarounds, but I've yet to get it working on anything more recent to date.
The 13 "real GPU" limit is DEFINITELY not a wanted feature - it may be a bug but I'm more inclined to think it's a "design decision for NO real or sensible reason".
ASUS seems to be VERY VERY slow about getting an update out to fix the issue - they appear to think that forcing folks to use a specific TYPE of GPU is acceptable, or whatever is causing them to have set that limitation up is being more difficult for them to FIX then they expected.
If you can get the board close to it's $150 MSRP, it's still a good option for a rig in the 8-13 card range, though perhaps somewhat overkill for the lower end of that range.
The built-in PS management features are nice, and make the ACTUAL price a lot closer to all other options in that range then just the "raw price" compare would indicate.