Windows has limited max 8 GPUs on the system, and Linux (13 maybe). But with a few trick, we can add more than 8 GPUs on Windows.
People out there even try so hard to set up 10-13 GPUs. And stability issue will be the main problems for broke the limit.
People out there even try so hard to set up 10-13 GPUs. And stability issue will be the main problems for broke the limit.
Max is 13 GPU for one rig, on special btc+ mobo's, but remember what 13 gpu will run only under linux
You are totally wrong , incorrect !!! And probably talking about something you don't have any experience
You dont need any trick to use more than 8 AMD or Nvida gpus on one system under windows , as the new amd driver / nvidia driver and a windows update support 12 cards , and with some trick you can make a few extra amd or nvidia cards to work on top of that 12 
You can run 12 AMD RX or 12 Nvidia cards easy under windows , and if you know what you doing how to set up your rig properly , you not going to have any problem !
if you want more than 12-13 cards , you must to mix nVidia / AMD / And mining cards
With ASUS B250 MINING EXPERT its possible to run more than 19 GPU's under windows , but you have to mix nVidia / AMD / And mining cards .
12 AMD Radeon RX 470 on one rig + 8 Mining cards
thats 20 under windows13x1080TI Windows 10 - 1709
13 AMD Radeon RX 470 on one rig + 8 Mining cards
thats 21 under windows