Exact notes from Manufactures website:
Compatibility:
Max. length graphics card 40 cm
Max. height CPU cooler 16 cm
Max. length PSU 29 cm
The case will standard support a GTX 560 ti, 570, 580, 670, 680 and most any high end minus DUAL GPU cards. The 40cm translate to a total of 15.75 inches. Some graphics cards are that long but most high end average around a foot long. So far as breathing room you should be ok. Cable management won't be easy at all so cables may be a mess. I highly recommend you get a Modular Power supply for your build.
http://www.sharkoon.com/?q=en/content/t28