Is it possible to successfully mine with 470 and 280x in one rig ? Which version of driver will be the best choice?
Yes of course. Mixed combinations work normal. Tested with 16.11.1 drivers, all works normal and good speed.
AsRock FM2+ BTC Board, Win7/x64 Ultimate, 6xGpuMod.
is there some modded bios for 390 improving mining? 
Yes, but not publicly available in most cases. If you have many cards, PM me for custom mod. ~5% speed increase guaranteed.
Thinking of buying a 390 for mining, and I know many people have already asked this, but what are the stock hashrates for a single card in claymore 11.1?
Thanks in advance.
Thanks in advance.
~370+ H/s @ 1085/1500MHz, -65mV
guys please answer to my question
how many gpu windows 7 64 bit can support?
how many gpu windows 7 64 bit can support?
5x Polaris Cards 100%, 6 Cards ... hardly, on boards i tested (AsRock BTC, Intel and AMD).
Maybe in mixed configurations (ie: 4x Polaris + 2x Hawaii/Tahiti/Tonga) can work, didnt have time to test, though
b.r.
ALex