ethOS is quite popular OS.
About tweaking the GPUs refer to https://bitcointalk.org/index.php?topic=1954245.0

I went with Windows 10 Professional. I bought OEM copy off ebay for $47 from someone with hundreds of satisfied customers.  I then installed Nicehash. Done.  They tweak all cards for you and start generating you cash immediately.   Also you can transfer your daily earnings from nicehash internal wallet to coinbase instantly with no fees, which is good for me.  I am not concerned about the hack back in december where $67 million was stolen, since I can transfer the $20 something dollars I make each day into coinbase for free.. worst case scenario I'd lose like $20.