I have a case 173B equipped with a Asrock motherboard H55M-MXM and a GT 425 M video card. One day, the case refused to start, and after an exchange card motherboard, always with the same symptom I suspect the video card. Asrock does not have in stock (after a discussion with their services) GT 425M model, I went to other models in the same format (MXM 3.0). Out, I'm on my second purchase video card (GT 130M and GT 250M), and always the same thing: everything works except the installation of video drivers. Windows 8.1 and Windows 7, it fails to install them. Mac OS X Lion Mountain and Maverick, the operating system will detect the correct version of the graphics card but can not get either to install my driver. Is it a problem of faulty motherboard or the final Asrock have voluntarily restrained the motherboard? thank you in advance and sorry for my bad english (I'm French). :)