Given the situation of no limit and/or preference i'm just gonna put a list for a Pc build.
1 - Get a Big Case for all those parts
2 - get one of the best Mobos
3 - Get ridiculous overkill on GPU power
4 - Awesome CPU
5 - Great Sound Card
6 - A few HDDs and SSD would not hurt
7 - Windows 8.1 Pro
(Please note that u need to include giant PSU (1000+), the remaining Fans for case, and so on)
1:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811146097
2:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131974
3:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487007 (double, triple or even quad SLi) (careful with PSU power)
4:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819116901
5:
http://www.newegg.com/Product/Product.aspx?Item=N82E16829102050
( Also think about getting very good headsets like the Logitech G930, A good Mechanical Keyboard, great gaming mouse and mat, Good flight stick (if into flying games) a very good surround sound and if u can a 3+ monitor set up)
(PLEASE NOTE: These parts are according to my preferences, yours can be different, also research which extra accessories you might need in the cause you pick such or similar parts)
Happy Gaming