OP there are HD 7950 cards which are less than or equal to 11 inches long.
Sapphire HD 7950 vapor-x is 10.83 inches (275 mm) long
XFX HD 7950 DD is 10.5 inches (267 mm) long
MSI HD 7950 twin frozr is 261 mm long. there is also a MSI HD 7950 twin frozr which uses a HD 7970 PCB which is exactly 11 inches (279 mm long)
here is the MSI HD 7950 twin frozr (HD 7970 PCB) fitting in an ANTEC 300 which supports max length of 279 mm
here is a user who bought the sapphire HD 7950 vapor-x from amazon. dual 8 pin version. this version has very positive user feedback. you can check card length with this user and ask any other questions
i recommend saving up the extra money and going for a Sapphire HD 7950 Vapor-x. the XFX DD cooler is not so good. the msi hd 7950 twin frozr has poor quality control and few users complain of overheating due to improper TIM application at the factory. after proper cleaning and TIM reapplication they were able to resolve the problem. good luck with whatever card you choose. Edited by raghu78 - 2/5/13 at 11:57pm