Hi,

Ever since I replaced the graphics card om my mac, the two usb-ports on the back of my apple studio display (LCD 17" model M7649) don't work no more (see also thread http://www.mac-forums.com/apple-desktops/28554-graphics-card-failure.html)
More people seem to experience similar problems http://discussions.apple.com/thread....1052&tstart=60

How can I figure out if this is a software or a hardware issue?

Thanks,
Vincent